Valeoscope Commercial Vehicles Clutch 2020

Transmission Systems Heavy Duty Clutch

valeoscope

Technical handbook

2020-2021 pln

Our origins in 2 LETTERS

T RU S T T H E T RAN SM I S S I ON S Y S T EMS S P E C I A L I S T

"Trust the Transmission Systems Specialist"

All Valeo friction materials are free of asbestos, lead organic solvents, ceramic and aramid fibers to ensure secure clutch repair operations by mechanics and the minimum impact on the environment. Valeo is the only manufacturer not using aramid in all its facings. All our clutch products are covered by a 2 Year Warranty, Unlimited mileage in Europe, on all kits and components either it is a New or a Remanufactured product. Find out more on valeoservice.com ●● Improved visibility and readability on Tecdoc ® ●● Improved data on Valeo Service technical platform, Valeo Tech@ssist

With a strong leadership in Original Equipment and more than 30 years in remanufacturing, Valeo provides one of the best offers in commercial vehicle clutches. The premium Clutch kit offers extremely high quality and performance for all commercial vehicles requirements, covering approximately 95% of the European commercial vehicles range with about 700 part numbers, comprising kits and components. The Valeo offer includes a large range of light commercial vehicles, coaches and heavy duty clutches to suit applications from all around the world, ensuring strong compatibility for all major heavy duty manufacturers. Beyond a large coverage, Valeo leverages its ability to deliver the latest applications on the market. Valeo thus provides a full range of clutch kits for main Truck Bus and coach Euro 6 applications such as DAF, FORD, IVECO, MAN, MERCEDES-BENZ, SCANIA, RENAULT TRUCKS, VOLVO, EVOBUS and SETRA. With the latest TH damper evolution, Valeo supplies the best possible powertrain solutions for the commercial vehicles industry, with a focus on reducing fuel consumption, while maintaining power and torque transfer from the engine to the gearbox. Valeo experience in frictionmaterials is a key element granting optimized comfort and greater Total Cost of Ownership (TCO) on both robotised transmission (material F830™) and manual transmission (material F510™).

THE VALEO SERVICE OFFER > Strong O.E. pedigree* > Coverage rate of 95 % in Europe > 354 clutch kits* for Medium and Heavy Commercial Vehicles > Genuine technical support featuring

• Quick and intuitive part search engine • All technical information in a few clicks • On demand training modules

●● Technical Hotline and Connected Assistance to get quick and professional answers about crosses, application requirements or fitment issues. ●● Technical training and promotion with our longstanding automotive professional trainers who know the aftermarket.

Tech'Care and Tech@ssist > 2 years warranty in Europe unlimited mileage**

* 279 kits are O.E. Clutch manufactured by Valeo 65 kits are matching quality manufactured by Valeo 10 kits are not manufactured by Valeo

** Warranty is applicable in Europeen Union 28 countries added by Norway, Iceland, Switzerland, Macedonia, Montenegro, Serbia, Bosnia, Albania and Kosovo for truck clutch applications (diam.>267 mm) under normal conditions of use and service. For more information please contact you local dealer or refer to Valeo Service General terms and conditions

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valeoservice.com

Table of Contents

1. Valeo clutch and actuation for heavy duty 1.1 Valeo clutch for heavy duty

3.3.3 Breakage of the fork contact area

46

3 Example of clutch Pull type 430 with fixed release bearing 4 Example of clutch Pull type 430

63

11 Dust or pieces of facing between the cover and the pressure plate 12 Breakage of the sleeve on the fork

32

3.3.4 Judder caused by grease

46

63

33

with snap on/off release bearing

contact area 13 Judder caused by grease 14 Disconnected pre-damper 15 Borken retainer plates

6 6 7 8

3.3.5 Seized tube-guide/ seized sleeve

46

33 34 34

1.2 Why Valeo clutch kit? 1.3 Clutch general 1.4 Clutch disc 1.5 Clutch cover 1.6 Release bearing 1.7 Actuation system

4.3 Recommendations for

64

3.3.6 Seized fork on ball pivot /axis

46

Concentric Slave Cylinder

3.4 Noise and vibration

47

4.3.1 Prior to Fitting the CSC

64

3.1.4 Gearbox with synchromesh

35

3.4.1 Reasons due to the clutch

47 47 47 48 48 49 49 49 49 49

13 16 17

4.3.2 Fitting tips & specific warnings

65

3.1.5 Robotised Gearbox hard gear shifting 36

1 Damaged cover caused by friction

for hydraulic systems

2 Seized ball bearing 3 Broken damper spring 4 Worn or broken clutch disc

3.2 Clutch slippage or lack of

37

5. New and remanufactured parts

torque capacity 3.2.1 External factors

2. Preventive maintenance for vehicles 2.1 Verification in cold conditions

5 Broken facings, broken cushion pad

37 38 38

6. Glossary Flywheel

6 Disconnected pre-damper

1 Blue-stained pressure plate

7 Friction marks on the retainer plates

2 External reasons due to the clutch linkage:

72

21

8 Broken retainer plates

seized fork on ball pivot/axis

Clutch cover

72

9 Broken disc

2.2 Verification while driving 21 2.3 Verifications in warm conditions 22

3.2.2 Reasons due to the clutch

39 39

Clutch disc

72

3.4.2 Gearbox with synchromesh

49

1 Over-heated spots on the pressure plate surface (creeping) 2 Grooves on pressure plate friction surface made by facing rivets 3 Cracks on the pressure plate

Bearing

73

3.4.3 Facing bonded on steel-back

49

40

Fork

73

3. Diagnosis

Clutch housing

73

4. Preventative maintenance 4.1 Examination and refit of

3.1 Hard gear shifting 23 3.1.1 External reasons due to the gearbox 23 or to the gearbox linkage (manual gearbox)

40 41 41

Tube-guide

73

4 Deformed pressure plate

51

Clutch linkage

73

5 Rubbing of the rivets after total wear od the facings 6 Stripped yarn after destruction

the clutch environment

4.1.1 Engine

51

42

3.1.2 External reasons due to the

25

of the facing binder

4.1.2 Gearbox

53

clutch linkage

7 Burst facing

42 43 43 44 44 44 44

8 Broken pressure plate

3.1.3 Reasons due to the clutch

26 26 27 27 28 28 30 30 31 31 32

4.2 Recommendations for a correct 54 assembly of the clutch kit 4.2.1 Clutch disc 54

9 Seized tube-guide/seized sleeve 10 Friction marks on the retainer plates

1 Deformed locking ring

2 Worn or broken system attachments

11 Broken disc

3 Worn diaphragm fingers

12 Diaphragm radial breakage

4 Deformed straps

4.2.2 Cover assembly

55

13 Dust or pieces of the facing between

5 Worn facing with cavities and

1 Cover assembly tips 55 2 Cover assembly centre with shipping clips 56 3 Cover assembly centre without shipping clips 57 58 1 Cover assembly with fixed release bearing 58 2 Cover assembly with snap on/off 61 release bearing

the cover and the pressure plate

shiny surfaces 6 Partially burst facing

3.3 Lack of smoothness/progressivity 45 3.3.1 Judder caused by shiny spots on the facing 45

7 Dirty splines/oxidation on splines

8 Worn and seized splines 9 Damaged pilot bearing 10 Diaphragm radial breakage

4.2.3 Release bearing

3.3.2 Deterioration of the cover assembly centring

46

4

5

Single disc clutch kit

1.1 Valeo clutch 1 Valeo clutch

and actuation for heavy duty

Twin disc clutch kit

for heavy duty Thanks to the O.E. position, Valeo is able to offer you a complete range of clutches in the aftermarket. Our catalogues cover all the needs for the professional: ●● Light commercial vehicles ●● Medium trucks ●● Heavy Trucks ●● Buses & Coaches A constantly increasing coverage that reaches up to 95% today. The list of covered applications is becoming larger and larger with the brand new Euro 6 applications. 1.2. Why Valeo Clutch kit? ●● Valeo truck clutches: the choice of quality. ●● One truck out of two is fitted with a Valeo Clutch. ●● Valeo supplies clutches to truck manufacturers all over the world. ●● Best in class clutches that allow the transmission of the highest torque with an optimized filtration of the vibrations for the driver's comfort and the driveline protection. Product design is following the Original Equipment specifications.

1.3 Clutch General Clutch composition A ingle disc clutch kit is composed by a clutch cover, a clutch disc and a release bearing. Function The clutch is a very important part in the driveline, it is located between the engine and the gearbox. The functions of the clutch are: ●● Transmit 100% of the engine torque to the gearbox ●● Interrupt the transmission of engine torque quickly and completely ●● Damp out the vibrations coming from the engine (acyclisms) ●● Allow modulation of the transmitted torque by slipping (move off, gear shifting, maneuvers) ●● Protect the drivetrain

Clutch torque capacity The clutch torque capacity means the amount of torque that can be transmitted by the clutch when it is fully engaged. It depends on different parameters: Tc = P x F x N x R Tc = Torque capacity (Nm)  P = Cover assembly pressure load (N)

 F = Friction coefficient of the facing material  N = Number of facings (2 for single clutch disc, 4 for twin-disc clutch)  R = Clutch disc radius Safety coefficient

To ensure a full torque transmission in any conditions, a safety coefficient is applied to the engine torque:

Clutch torque = engine torque × K (safety coefficient)

The safety coefficient (K) is 1,15.

6

7

Valeo clutch and actuation for heavy duty

1.4 Clutch disc The clutch disc is a part linked to the primary shaft of the gearbox and fitted between the flywheel and the cover assembly. It allows to damp out the vibrations coming from the engine and to transmit progressively the torque to the gearbox.

The characteristics of each clutch disc are designed following the driveline on which it has to be fitted. On modern products, a second damper, called pre- damper, is used to avoid noises coming from the gearbox syncromeshs and gearbox chattering when the vehicle is in neutral at idle speed. This damper is located between the main damper and the hub. Its filtering capacity is lower than the main one. Cushion disc: This system has an undulating surface which provides a spring characteristic during clutch engagement and disengagement phases. It is located between the two facings and allows a progressive torque transmission, for the driver comfort. 1. Disc in declutch position (No diaphragm effort) 2. Compression of the set (disc+facings) by the diaphragm effort 3. Full compression of the set (disc+facings) by the maximum diaphragm effort Advantages of cushion: ●● The pressure plate is subjected to high thermal changes. In hot conditions, it has a convex shape while a concave one in cold conditions. Thanks to the cushion disc, the facing remains in full surface contact with the pressure plate whatever its deformation, in normal working conditions. Without cushion disc, the clutch engagement is jarring and uncomfortable for the driver and can generate clutch slippage. ●● Reducing judder. Twin disc clutch Twin disc clutch kit consists of a clutch cover, two clutch discs, an intermediary pressure plate and a release bearing. Valeo already launched several part numbers for some Mercedes-Benz, Renault-Trucks MAN and Volvo applications.

Guide washer

Disc (Cushion)

Rivet (disc)

Spring

Hub

Pre-damper

Load

1

3

Spring (pre-damper)

Steel backing

2

2

Facing

Flenge

Friction washer

1

3

The clutch disc is composed of: • a splined hub for the fitting on the primary shaft • a metallic part, on which two facings are riveted. On modern applications, the clutch disc is designed with a damper to absorb vibrations from the engine and with a cushion disc to allow a smooth clutch engagement and a 100% torque transmission. Damper working principle In different parts of the transmission, filtrating vibrations coming from the engine is an important and a difficult issue. To do this very important operation, a damper is fitted between the facings (linked to the engine) and the hub (linked to the gearbox primary shaft). During the running of the vehicle, the damper, thanks to its angular deflection, will absorb the engine vibrations and the torque variations due to gear shiftings and accelerations/decelerations of the vehicle.

Clutch disc

Disc thickness under maximum diaphragm effort

Displacement

8

9

Valeo clutch and actuation for heavy duty

Intermediary pressure plate

Cover assembly

Flywheel side clutch disc

Gearbox side clutch disc

Release bearing

Composition of twin disc clutch kit

Clutch Facing F830™

Clutch Facing F510™

Facing The facing role is to transmit the full engine torque. For this reason, they have to be selected according to the following criteria: ●● Friction coefficient: It is the ratio between the force F needed to move an object on a surface and its weight. It depends on the contact surface size. It is essentially related to the nature of the surface. The coefficient for a tire on ice is very low, and close to 0. On dry asphalt, this coefficient can be more than 1. For clutch, the facings are in contact with the flywheel and with the pressure plate. ●● Wear on the facing: It determines the life duration of the friction material. ●● Mechanical resistance: Burst and elastic stress (gymnastics).

Twin-disc advantages compared with single disc clutch 1. Wear capacity increased from 3mm to 5,5mm; 2. Better thermal adaptation for severe applications: Overloaded trucks Construction Life duration is multiplied by 2 to 4 in severe usage; 3. Increased damper capacity (engine torque shared between 2 discs);

●● Thermal resistance: applications to high thermal stresses. ●● Aggression resistance: wear and scratches on the flywheel and the pressure plate. ●● Comfort: It means torque transmission progressivity and decreased risk of icing. Inertia Inertia is the clutch disc resistance to changes in its rotating state when there is a gear shifting. The smaller the inertia, the quicker the gear shifting. Valeo’s commitments on facing ●● 100% environmentally friendly material: Valeo banned chlorinated solvents and aramid fibers in addition to asbestos and lead. Valeo friction materials can be 100% recycled when dismantled.

4. Increased damper durability (engine torque shared between 2 discs); 5. More reliable as they are sold as kits: The parts are made to be fitted together which is not always the case with separate components; Guaranty of a more reliable repair for the final customer.

10

11

Valeo clutch and actuation for heavy duty

1.5 Clutch cover

●● Premium performance, long life-time: In terms of performance, Valeo facings deliver high and stable friction levels, excellent fade resistance and increased life time, resulting in improved driving comfort and low cost of use. Valeo Friction Materials develop facings with the same chemical formulas, production processes and quality all over the world.

●● In heavy duty clutch, Valeo facings offer addresses all segments of vehicles from construction vehicles to long haulage with specific products adapted to their environment and to gearboxes sensitiveness.

Strap

Diaphragm

Articulation ring

Clutch cover

F510™ MCC F510™ F830™ F830+™

NO

Heavy metal

Aramid fibres

Organic solvents

2,08

1,92

1,63

1,65

Density [g/cm 3 ]

Friction level stability vs energy & t°

+

++

++

+++

Cup

Plate rivet

+++

++

+

+

Thermal resistance

Pressure plate

+

+++

+++

Judder (hot conditions)

Hooked ring

Cover rivet

Very severe

Severe

Long Haul

Type of usage

Clutch cover

Valeo facings range and application types

Push-type and Pull-type cover assembly technologies:

The cover assembly is designed with the right clamp load to allow the transmission of the engine torque and to limit slippage during the gear shift. The cover assembly consists of the diaphragm, the pressure plate and the cover among which, diaphragm plays the most important role. In Valeo, we carefully follow a precise heat treatment process on each processes of each diaphragm, in order to achieve their high quality.

Modern commercial vehicles are fitted with different types of clutches, depending on the truck manufacturer request. The two principal designs are, push and pull type clutches.

Testing on disc Valeo is using very severe testing criteria, which are exactly the same for both O.E. and IAM parts. Different tests are done: ●● Endurance test ●● Structural reliability test ●● Burst resistance test ●● Hysteresis measurement ●● Truck fitting and running tests

P R N D

RECOMMANDED FOR ROBOTIZED TRANSMISSION

Valeo provides the solution to judder effect on robotised gearboxes: F830™ is recognized by truck manufacturers for this transmission type.

12

13

Valeo clutch and actuation for heavy duty

Push-type cover assembly On a push type cover assembly, the release bearing pushes the diaphragm toward the flywheel, to disengage the clutch. Pull-type cover assembly On a pull type cover assembly, the release bearing pulls the diaphragm away from the flywheel, through a connection system. The difference between the two technologies is the position of the articulation of the diaphragm inside the cover. This means that the lever arm between the diaphragm articulation and the release bearing contact on the diaphragm is longer in case of pull- type cover assembly than in case of push-type.

So, for a pull-type cover assembly, the release bearing effort will be lower up to 30% compared to push-type design. Therefore, for the same release bearing effort, the clamp load of the clutch can be increased by 30%. To summarize, the pull type system benefits are:

The advantages of the Valeo Self Adjusting Technology are: ●● High torque capacity ●● Compact and robust design ●● Reliable: compact design as the S.A.T. device is integrated in the clutch cover. Axial compactness due to increased release travel. ●● Easy to fit: Valeo S.A.T. does not require special tools for installation. It can be installed using standard garage equipment. ●● Comfortable: constant diaphragm spring position, constant release bearing effort.

●● Lower release bearing effort ●● Cover deformation reduced ●● Reduction of pressure plate lifts loss

Test on Cover

●● Durability test ●● Performance test clamp load and release effort ●● Burst strength ●● Vehicle fitting test

Gearbox side

Diaphragm articulation

Self Adjusting Technology (S.A.T.) A development of the modern clutch is the self adjusting system, which ensures the same diaphragm finger height throughout the whole life of the clutch, maintaining limited and constant release bearing effort and, limited impact on the crankshaft of the engine. Self Adjusting technology working principle The facings wear is compensated by the cover assembly through a fulcrum with ramps which can rotate, allowing a modification of the pressure plate height. This incremental actuation is done by an operating spring which manoeuvers a screw and ratchet wheel fixed on the fulcrum with ramps at each clutch engagement. This operation is activated at each clutch disengagement and as soon as a certain level of facings wear is reached, the ratchet wheel can rotate to jump to the next teeth and modify the pressure plate height through the fulcrum. The position of the diaphragm remains always the same, allowing a constant release bearing effort.

Release bearing

Flywheel side

Pressure plate

Push-type diaphragm

Gearbox side

Release bearing

Diaphragm articulation

Flywheel side

Pressure plate

Pull-type diaphragm

14

15

Valeo clutch and actuation for heavy duty

1.6 Release bearing The release bearing applies the disengagement efforts on the diaphragm through a determined stroke. ●● Sleeve: Specific to each type of gearbox and clutch linkage. ●● Ball bearing: Specifically designed to absorb the declutching efforts, and to work in more and more difficult conditions (temperature, dust). ●● Self-centering release bearing: The self-centering system allows a radial displacement of the ball bearing to be aligned with the axis of cover assembly to avoid the diaphragm fingers wearing. This auto-alignment is done when the mechanic starts the engine after the clutch replacement. Release bearing for Push type clutch This type of release bearing pushes on the diaphragm without a device. The release bearing contact on the diaphragm can be: ą ą toric for diaphragm with flat fingers ą ą flat contact for diaphragm with bombed fingers.

1.7 Actuation Clutch Master Cylinder (C.M.C.)

Fixed type release bearing The fixed release bearing has to be fitted on the diaphragm by a locking system before the assembly of the set on the flywheel. In case of complete kits, the release bearing is fitted by Valeo directly on the cover assembly.

The clutch master cylinder is connected directly to the pedal. The pressure applied to the pedal pushes the piston along the path inside the cylinder. The piston translates this force into hydraulic pressure and a volume flow, transferring it to the clutch slave cylinder or concentric slave cylinder via the clutch pipe.

Nr.

Part name

1

retaining ring

2

housing

3

cap

4

rubber plug

5

bushing

Fixed type release bearing

6

ring

7

spring

Snap-on/off release bearing This system consists of a hook cup system assembled on the diaphragm of the cover assembly and of a release bearing using a specific ball bearing shape. This release bearing is connected on the cover assembly once the gearbox is fitted back on the engine, with the help of the fork.

8

hood

9

plate

10

piston

11

sleeve

12

lip ring

13

sleeve

14

snap ring

15

protecting cap

16

piston rod

Clutch Master Cylinder

Flat contact bearing

Toric contact bearing

Snap-on/off release bearing

Release bearing for pull type clutch This release bearing needs to be connected to the diaphragm with a device. There are two types of pull-type release bearing:

ą ą fixed release bearing ą ą snap-on/off bearing.

16

17

Valeo clutch and actuation for heavy duty

Concentric Slave Cylinder (C.S.C.) The C.S.C. is also a receiver and operates directly on the clutch cover diaphragm. The C.S.C. replaces the clutch release cylinder (C.R.C.) and eliminates the release bearing, the guide tube and the clutch fork from the system. The concentric slave cylinder has a plastic housing and is designed for an operating pressure of up to 40  bar. To gain more space, it is designed in two parts and it is equipped with a steel guide sleeve. This enables small axial and radial sizes. The concentric slave cylinder uses a large coil spring to maintain constant contact between the release bearing and the diaphragm.

Clutch Release Cylinder (C.R.C.) The clutch release cylinder is combined with a mechanical classic gearbox. It is composed of the piston, cups, spring, push rod and covered with a caoutchouc cap. The cap provides protection from dirt, dust and debris from contaminating the push rod and piston.

When the clutch pedal is pressed and the fluid pressure reaches the release cylinder, the piston moves the push rod out to apply force onto the clutch fork which releases the clutch. When the clutch pedal is released, the hydraulic pressure and the force of the return spring pulls back the push rod and sends back the fluid to the master cylinder, therefore engaging the clutch.

Sleeve

Circlip

Spring

Housing

Filter

Outer ring

Sliding sleeve

Sealing ring

Disc

Inner ring

Sensor assembly

Sliding sleeve

Plate spring

Sealing washer

With brake fluid

With mineral fluid

Nr.

Part name

1

tension ring

2

protecting cap

3

retaining ring

4

push rod

5

piston

6

ring

Concentric Slave Cylinder with/without sensor connector

Concentric Slave Cylinder without sensor

7

spring

The concentric slave cylinder has to be replaced at the same time as the clutch. In the case of robotised gearboxes, the actuation is made via an electronic unit associated with a hydraulic power unit, eliminating the clutch pedal. A sensor is attached to the C.S.C. to detect the stroke of the bearing which informs the position of the clutch.

Our C.S.C. equips mainly Mercedes-Benz (until Euro5) and a few MAN medium range of vehicles. The liquid can be either Dot 4, Dot 5, braking fluid or mineral fluid. The efficiency is increased as the deformations under load and the pedal load are reduced. The C.S.C. is concentric to the primary shaft which is an advantage for the truck manufacturer due to a reduced number of components.

8

housing

9

bleeder

10

closure plug

11

ring

12

screw neck

13

closure plug

18

19

Preventive maintenance of vehicle

Electro-hydraulic Clutch Actuator The electro-hydraulic clutch actuator takes the place of the master/slave cylinder and of the clutch pedal. It automatically opens and closes the clutch. Designed for highly dynamic, precise clutch control in commercial vehicles, the compact plug & play unit combines mechanical and hydraulic action with sensors and electronics. The driver´s benefits: highly precise maneuvering, easier docking, safer uphill driving and fuel saving. ●● A brushless DC motor drives a hydraulic piston by a spindle ●● The displaced brake fluid volume is used internally for the operation of a slave cylinder ●● In connection to the integrated control electronics and a displacement sensor, the actuator decodes an electronic set point signal into the positioning of a piston rod and also serves for the immediate operation of a clutch open levers. ●● The unit is delivered with brake fluid, so the user just has to dock the device mechanically and after docking the electricity the clutch can be controlled electronically. ●● The components are designed for the rough operation conditions and the high loads in the commercial vehicle. ●● By the combination of electronics, sensors, hydraulics and mechanics the requirements in high precision and dynamics as well as a long lifetime under extreme environment conditions can be met in spite of a compact construction.

Clutch booster A clutch booster is fitted instead of a C.R.C. (Clutch Release Cylinder) and its main action is to push (or pull) the fork in order to clutch (or declutch); it is linked to a CMC (Clutch Master Cylinder). Its function is to convert and amplify non hydraulic pressure into hydraulic & pneumatic pressure. A clutch booster is only used in a manual transmission configuration and especially defined by the O.E. manufacturers requirements.

2

Vehicle preventive maintenance

2.1 Verification

2.2 Verification

in cold conditions Engine, oil and coolant temperature are low at first engine start conditions. Check the following points: ●● Clutch pedal load ●● Disengaging and engaging points ●● Clutch pedal position (relative to floor) ●● Gearbox range switch (must always occur after declutching point) ●● Clutch engagement (smooth engagement) ●● Comfort during operation (no judder) ●● Inertias (time to engage reverse gear) ●● Noise (gearbox noise or during clutch operation)

while driving

●● Test of gear shift ●● Test of gearbox range and split shift

●● Noise (of gearbox or during clutch operations) ●● Torque transmissions (after up-shifting, full throttle) Example: Reach the speed of max torque in 4 th gear. Shift quickly to the 5 th gear and fully depress the accelerator pedal, then re-engage quickly. The engine speed and vehicle speed must increase simultaneously.

Clutch booster

D = Declutch R = Engagement S = Synchronized 1 = Correct 2 = Delayed 3 = Slippage ω = Rotation speed of maximum torque

Gear shift

ω

2

1

3

D = Declutching point E = Engagement point R = Gearbox range shift point

Rotation speed (rpm)

D

R

S1 S2

Time

Attention Ɂ Ɂ To check the torque transmission, the “stall test” must not be done (full torque, vehicle stopped, parking brake engaged). This test can deteriorate the drive train and the clutch.

Advice   When the clutch linkage is in good condition, the clutch pedal should promptly return to its position. The points of engaging and disengaging should not be situated too close to the end of pedal travel (generally at 2/3 of the travel), in order to allow the range shifting in disengaged position and to get a good grasp of the cushion through an ergonomic position of the feet of the driver.

Advice   A functional and well set clutch actuation always results in a straight return of the pedal.

Electro-hydraulic clutch actuator for Scania

20

21

Diagnosis Hard gear shifting

2.3 Verifications in

R 1 3

3

warm conditions (Manual gearbox only) Engine, oil and coolant temperature are in normal working conditions. ●● Same verifications as in cold conditions, ●● Clutch disc release (no sticking), ●● Disengagement travel: At clutch pedal At clutch release cylinder At clutch fork At release bearing At pressure plate (check according to truck manufacturer specifications) ●● Check the facing wear (to be done according to truck manufacturer method). Measuring the engaging time of reverse gear Conditions: ●● The vehicle is stopped. ●● Gearbox and clutch at usual operating temperature. ●● Engine at idle speed (check that the idle speed is within the manufacturer specifications). Measurement method: ●● Evaluate the necessary time to engage, without a scratching noise , the reverse gear or the 1 st gear if it does not have synchromesh (In warm conditions, the engagement time is longer than in cold conditions). ●● Proceed by successive steps starting with a very short time (1 second) or with the max acceptable time (7 seconds).

RECOMMANDED FOR MANUAL TRANSMISSION

2 4

Diagnosis

Example: ●● Declutch, wait 1s, engage the reverse gear = scratching noise ●● Declutch, wait 2s, engage the reverse gear = scratching noise ●● Declutch, wait 3s, engage the reverse gear = scratching noise ●● Declutch, wait 4s, engage the reverse gear = no scratching noise

3.1 Hard gear shifting 3.1.1 External reasons due to the gearbox or to the gearbox linkage (Manual gearbox)

Engagement time without a scratching noise in 4s = correct

Attention Ɂ Ɂ With some gearboxes (oil at operating temperature), it is sometimes necessary to wait until 7 seconds to be able to engage the reverse gear without any scratching noise. Advice   If the reverse gear engagement time (without scratching noise) is more than 7 seconds, it is considered as abnormal (the average value is 3 to 4 seconds).

Inertia of the friction Inertia of the first shaft Inertia of the synchronisation ring

Inertia of the second shaft

Engine

Clutch

Gearbox

Transmission shaft

Gearbox inertia

22

23

Diagnosis Hard gear shifting

3.1.2 External reasons due to the clutch linkage Vehicle behavior ●● Difficulty in gear shifting when running or when the vehicle stops. ●● Gear noise (scratching noise) in reverse gear engagement. ●● Difficulty or inability to engage or disengage the gear. ●● Vehicle jumps slightly when the gear is engaged from idle position. Reasons ●● Pedal system: Jamming Wear Adjustments (Pedal height, Travel stopper pin) ●● Clutch linkage: Mechanical: Cable, sheath and stopper articulation axis (wear and jamming) Hydraulic & Hydro-pneumatic: Master and slave cylinder (leakage, adjustment) ●● Release travel is too short: repair of clutch linkage Diagnosis Measure the release travel: To determine if it is the clutch which causes the issue, we have to check the fork travel to estimate the release travel. ò ò Release travel too short  Repair of the clutch linkage ò ò Release travel conforms to specifications  Disassemble the gearbox from the engine and clutch inspection. Attention Ɂ Ɂ Do not disassemble the clutch unless the release travel is not correctly set according to the manufacturer's specifications. Advice   To have a good estimation of clutch release travel, the measurement must be done as close as possible to the clutch.  Check the presence of air in the hydraulic system (Bleed the hydraulic system according to the manufacturer’s specifications).

The travel A of master cylinder is not long enough due to a wrong adjustment of the pedal travel stopper screw 2. 

Vehicle behavior ●● Hard gear shifting while driving or when the vehicle is stopped. ●● Gear noise (scratching noise) when reverse gear is engaged. ●● Difficulty or inability to engage or disengage the gear. ●● In idle speed with clutch in declutch position, the vehicle moves with the gear engaged. Reasons ●● Gearbox (poor gear conditions or synchromesh…) ●● Gearbox shifting system (wrong conditions or incorrect shifting system adjustments, fork, …) ●● Inertia (time to stop the rotation of input shaft) ●● Inertia sensibility depends on the gearbox's design and its conditions. ●● It also depends on the lubricant's quality and temperature. Diagnosis ò ò In some gearboxes, the gears cannot stop immediately after declutching. Gear scratching noise happens during a fast gear engagement (mainly reverse gear, non synchromesh gear). To define whether the reverse gear's scratching noise is due to gearbox inertia or to a wrong clutch release, we can do as follows: ● ● Declutch and engage the gear  scratching noise. ●● Remain in declutch position, move the gearshift lever to idle position. ●● Wait for 15 seconds and engage the reverse speed. If no scratching noise  Gearbox inertia If scratching noise  Wrong clutch release Measurement method 1. Vehicle stopped. 2. Gearbox and clutch at normal operating temperature. 3. Engine at idle speed. 4. Evaluate the necessary time to engage the reverse gear without the scratching noise or the 1 st gear. 5. Proceed by successive steps starting with a very short time (1 second) or with the max acceptable time (7 seconds).

Example ●● Declutch, wait 1s, engage the gear = scratching noise ●● Declutch, wait 2s, engage the gear = scratching noise ●● Declutch, wait 3s, engage the gear = scratching noise ●● Declutch, wait 4s, engage the gear = no scratching noise Engagement time without scratching noise in 4s = acceptable Attention Ɂ Ɂ If the time is more than 7 seconds, it is necessary to check whether it is due to gearbox inertia (gearbox lubricant, engine idle speed…) or wrong clutch release, which needs to be at 15 seconds. Ɂ Ɂ If the reverse gear can be engaged, the issue is not caused by the clutch or the clutch linkage. Advice   Check that all adjustments have been done according to the truck manufacturer specifications.  Even if the issue happens to only one or two gears, the conditions of the gearbox and its linkage have to be checked.

Pedal

Slave cylinder: The release travel C is not long enough due to wrong adjustment of release push rod X . 

Slave Cylinder

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Diagnosis Hard gear shifting

3.1.3 Reasons due to the clutch

1. Locking ring deformed

2. Worn or broken attachement systems

3. Worn diaphragm fingers

Vehicle behavior ●● Difficulty in gear shifting when the vehicle is running or when it is stopping. ●● Gear noise (scratching noise) when engaging reverse gear. ●● Difficult or impossible to engage or disengage a gear. ●● Vehicle jumps slightly when the gear engages from idle position. Reasons ●● Release bearing

Parts inspection The release bearing connection system is disconnected, broken or snatched. Vehicle behavior ●● Impossible to shift the gear. Reasons ●● Assembly or fitting mistake. Parts damaged during assembly. The release bearing connection part is not well positioned. The clutch disc has been fitted in a wrong position. ●● Snap ring or lock ring Not well positioned in the bearing groove or deformed during assembly.

Parts inspection The connecting system of the snap on/off release bearing is disconnected, worn, broken or snatched. Vehicle inspection The release bearing is disconnected from the diaphragm.

Clutch inspection Diaphragmfingers are worn by the bearing (Incrustation, wear, or breakage of diaphragm fingers).

disconnection wrong sliding ●● Cover assembly

Worn diaphragm fingers

cover deformation pressure plate broken straps straps deformation facings dirty with grease shock on facings shock on disc shock on splines

Vehicle behavior ●● Hard gear shifting. ●● Clutch Pedal vibration. Reasons ●● Wrong condition or incorrect adjustment of linkage ●● Damaged bearing ●● Engine malfunction ●● Severe usage ●● Fitting of a release bearing without self centring Diagnosis ò ò Insufficient release bearing preload (wear due to slippage between bearing and diaphragm fingers) ò ò Wrong condition of linkage (fork, articulation) ò ò Wrong Cover assembly setting ò ò Seized bearing ò ò A worn or wrongly calibrated engine will generate high vibrations at bearing/diaphragm contact ò ò The clutch fitted is not the right one ò ò The wear of diaphragm fingers depends on the clutch usage (very common in urban areas) Attention Ɂ Ɂ Only use products from a supplier delivering Truck manufacturers.. Advice   Checktheconditionofclutchlinkageandmake adjustment according to manufacturer’s recommendations.  Check the effectiveness of each operation of the release bearing preload system.

●● Clutch disc

Diagnosis ò ò The diagnosis can be done by measurement or observations through clutch housing opening. Attention Ɂ Ɂ Never clean the parts before their inspection. Advice   Parts inspection is performed after gearbox and clutch disassembly (Refer to examination of used clutch Chapter 4).

Fixed Release Bearing

Reasons ●● Poor condition of clutch linkage, insufficient bearing preload on diaphragm ●● Intensive engine vibrations ●● Wrong locking of release bearing attachment system during assembly ●● Forget to unlock the release bearing during gearbox disassembly (attachment system snatch when pulling away the gearbox) Attention Ɂ Ɂ Check the clutch linkage conditions, the engine and their adjustments. Advice   Follow specific Valeo fitting instructions for snap on/off release bearing. (Refer to maintenance tips).

Advice   Respect Valeo installation instructions (Refer to Valeoscope fitting tips).

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Diagnosis Hard gear shifting

4. Deformed straps

5. Worn facing with cavities and shiny surfaces

Parts inspection ●● The facing is shiny on most parts of the friction surface. ●● There are some cavities. ●● The facing rivets are not drilled. Vehicle behavior Wrong clutch release mainly in warm conditions, with: ●● Gearbox noise during reverse gear engagement (whatever the duration of clutch disengagement is). ●● Hard gear shifting while driving. ●● The vehicle tending to move, gear engaged in declutch position.

Deformed straps

Parts inspection Straps are deformed. Vehicle behavior It is impossible or difficult to shift gear. Reasons ●● Drop of the cover assembly before fitting (during transportation or handling). ●● Deformation occurred during cover assembly bolting operation (use of a lever between cover and straps or between pressure plate and straps to prevent rotation of the cover assembly). Diagnosis ò ò Wrong pressure plate lift  the clutch disc is not released completely. Attention Ɂ Ɂ Handle the cover assembly carefully; a shock on cover side can damage the straps. Advice   Check the straps before cover assembly mounting. The straps must be in contact with each other along with their total length and they must not show any bending mark.

Suction phenomenon

Reasons ●● The clutch disc cannot slide on the input shaft splines and stick to flywheel. Despite a good pressure plate lift, the input shaft is always in rotation. ●● Warm air is confined. Inside the cavities of facings (rivet holes, facing cavities) which create a suction effect with the flywheel. ●● This phenomenon happens more frequently on large size clutch discs (380 to 430 mm) in which the usage conditions are not severe (high frequency of gear change under low energy dissipation). Diagnosis ò ò It can be checked through the holes of clutch housing by using a stroboscopic lamp (if the clutch layout is compatible). Attention Ɂ Ɂ This issue is rather special when the clutch is a low quality reworked product (rivet type, facing material; non-grooved facing with steel back).

Clutch disc with grooved facings

Drilled rivet

Worn facing with cavities and shiny surface on outer diameter

Advice   To avoid it, use only Valeo productswhich have been designed for the correct adaptation.

Valeo Solution

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Diagnosis Hard gear shifting

6. Partially burst facing

7. Dirty splines/oxidation on splines

8. Worn and seized splines

9. Damaged pilot bearing

Parts inspection The facings are broken along the lines joining rivets, pieces of facing is snatched out and then are stacked. Vehicle behaviour Hard gear shifting  clutch does not release. Reasons ●● Partial burst is due to high rotation speed of the clutch disc (rotation speed higher than burst speed). ●● Mis-shifting or mistake of range shift position.

Parts inspection ●● It is difficult (sticking) or impossible (seizing) to rotate the pilot bearing. ●● The pilot bearing is destroyed (ball and ball cage destroyed). Vehicle behavior ●● It is impossible or difficult to shift gears. ●● This issue is wrongly associated to several reasons related to cover assembly or clutch disc. Reasons ●● The pilot bearing is dried due to overheating of flywheel. ●● Insufficient quantity of grease inside the pilot bearing (grease has been ejected due to air pressure during introduction of gearbox input shaft). ●● Deterioration of grease (aging, drying, facing dust…). ●● Deterioration of ball cage during gearbox assembly (shocks of gearbox input shaft). ●● Wrong positioning of the pilot bearing.

Dirty splines / oxidation on splines

Worn and seized splines

Parts inspection ●● The clutch disc splines are clogged (grease and dust…). ●● Oxidation marks on both clutch hub splines and input shaft splines; seizing is due to the lack of greasing. ●● The input shaft splines are damaged (shocks, wearing or caulking). Vehicle behavior Hard shifting for each gear because of insufficient displacement of the clutch disc on the input shaft. The facing remains in contact with the flywheel. Reasons ●● Grease was not applied on splines during assembly operation (or insufficient quantity of grease was used). ●● No suitable grease has been used. ●● Damaged splines. Attention Ɂ Ɂ Valeo has designed hub nickel plated clutch discs that do not require greasing. In such cases, specific instructions are provided with the disc. Advice   Use appropriate grease recommended by the manufacturer if necessary. (Refer to Valeoscope maintenance chapter)

Parts inspection ●● Splines are worn or caulked ●● Shock marks on side of splines Vehicle behavior Shifting is difficult for each gear, due to wrong disc sliding on the input shaft of the gearbox. Reasons ●● Wrong handling during assembly (shocks during ●● Wrong disc part number has been used (Splines dimensions do not match with the gearbox's input shaft). ●● Large engine vibrations. Advice   Check if the disc used fit the gearbox (check the part number).  Center the disc with the appropriate tools and carefully mount the gearbox.  Check the engine's conditions and adjustments. gearbox mounting operation). ●● Misalignment engine/gearbox.

Partially burst facing

Attention Ɂ Ɂ Gearboxes require careful handling. Such issues may occur while mis-shifting or when using “repaired” products.

Pilot bearing damaged

Attention Ɂ Ɂ Check the positioning and the holding of the pilot bearing (wear of bearing housing or wear of gearbox input shaft tip). Carefully assemble the gearbox.

Advice   Replace the pilot bearing each time you replace the clutch.

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Diagnosis Hard gear shifting

10. Diaphragm radial breakage

11. Dust or pieces of the facing between the cover and the pressure plate

12. Breakage of the fork contact area

13. Judder caused by grease

Parts inspection Wear or breakage on the fork contact areas. Vehicle behavior Generally, such issues can affect the clutch operation in: ●● Hard declutching ●● Unsmooth clutch engagement ●● Hard shifting

Parts inspection There is grease on the clutch facings Vehicle behaviour ●● It is impossible or difficult to shift gears ●● Slippage of clutch in hot conditions ●● Judder Reasons ●● Oil leakage from the gearbox or from the engine ●● Grease leakage from the pilot bearing ●● Excess of grease on the clutch disc splines or on release bearing sleeve

Parts inspection Dust or pieces of facing between cover, diaphragm and pressure plate. Vehicle behavior ●● Impossible or difficult to shift gears ●● Clutch slippage Reasons ●● Severe usage of clutch ●● Wrong conditions or wrong adjustments of the clutch linkage ●● Mistake in using the gearbox Diagnosis ò ò Facings destroyed because of overheating ò ò Centrifugation of facings ò ò Pieces of facings are spread inside the cover assembly

Radial breakage of diaphragm

Parts inspection Radial breakage of diaphragm Vehicle behavior ●● Impossible or difficult to shift gears ●● Slippage of clutch Reasons ●● Wrong adjustments of the clutch linkage ●● Clutch linkage out of specifications Diagnosis ò ò Such issues often happen due to the excess of bearing travel. ò ò The diaphragm stress has exceeded its mechanical resistance. Attention Ɂ Ɂ Check conformity and function of the clutch linkage parts. Ɂ Ɂ Follow the manufacturer’s recommendations concerning their adjustment. Advice   Replace the 3 parts of the clutch kit.  Check the bearing travel and the condition of the actuator  Be aware of diaphragm spring quality and characteristics of non-original products.

Breakage of fork contact area

Reasons Because the fork contact is not symmetrical, the consequences can be: ●● Insufficient bearing travel ●● Increased slipping time (reduced release bearing speed during engagement) ●● Rough vehicle startup (shocks, shuffle) Diagnosis ò ò Insufficient greasing on fork contact areas. ò ò Wrong condition of the fork or of its pivot system. ò ò Intensive use of the clutch due to the vehicle usage type generating fast wear at fork contact areas. Attention Ɂ Ɂ To insure good function and long life of your clutch, it is necessary to apply appropriate grease at the release bearing/fork contact areas. Advice   Check and refit the clutch linkage (fork, axis, and pivot).  Replace the fork when its contact areas are damaged.  Grease the fork contact areas when the fork has no roller.  If the fork has rollers, make sure that they are not jammed; greasing the fork contact is not necessary.

Grease on the facing

Diagnosis The diagnosis is quite difficult and can sometimes be done through the clutch housing hole. ò ò Using a stroboscopic lamp, it is possible to see the displacement of the disc. ò ò Facing adhesion on friction surfaces (flywheel, pressure plate) prevents the clutch disc from moving along the splines. ò ò Facing friction coefficient has dropped and become unstable. It generates: • Unsmooth vehicle start-up (vehicle shuffles during clutch engagement in both forward and in backward). • Insufficient clutch torque capacity (mainly in hot conditions, full engine torque) Attention Ɂ Ɂ A clutch disc with facing contaminated by grease cannot be used again and must be replaced.

Dust or pieces of facing

Attention Ɂ Ɂ It is impossible to re-use a cover assembly covered with facing dust. It cannot be completely cleaned and has to be replaced. Advice   Check the conditions and the adjustments of the clutch linkage.  Replace 3 pieces clutch kit and clean the clutch housing.

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