Valeoscope Commercial Vehicles Clutch 2020

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.

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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

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