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Analysis of the reasons for the heavy clutch pedal: the five most common factors.
For small car drivers, short-distance driving is a joy. However, for professional drivers, driving is a physically demanding and heavy task. For professional truck drivers, the size of the vehicle, long driving hours, and work intensity are self-evident. If the clutch pedal acts up at this time, it can make the drivers feel even more mentally and physically exhausted.
The clutch pedal is one of the devices that drivers use frequently; it is needed every time they shift gears. If the clutch pedal is very heavy, it can torture your left leg after driving for a whole day. In fact, the design of the clutch takes the driver's operating strength into account, and under normal system conditions, it should not require too much effort to operate. However, if there is a problem, it can become very heavy. Today, I will analyze some common reasons that can cause the clutch pedal to be heavy.• Reason for heavy pedal: Strong return spring tension.
In order to ensure that the clutch pedal can accurately and quickly return to the standby position when released, a return spring is designed at the pedal point. If the phenomenon of a heavy pedal occurs after replacing with a new spring, it is likely caused by the return spring exerting too much force. This problem is relatively easy to solve; simply replace it with a spring that has a smaller force.● Causes of heavy pedal: damage to the clutch booster cylinder.
Currently, almost all heavy-duty truck clutches use a power assist system, which generally makes operation easier. However, if the clutch booster cylinder malfunctions, it may lead to insufficient assistance. The result is that the clutch pedal feels very heavy when pressed. If anyone experiences issues with a heavy clutch operation, it is advisable to check whether the booster cylinder is functioning normally. Additionally, low-quality booster cylinders are more prone to such problems, so it is recommended to choose products from reputable brands.● Reasons for Heavy Pedal: Low Compressed Air PressureI have previously mentioned that damage to the clutch booster cylinder can cause a heavy pedal, but sometimes the cause may not be the booster cylinder itself. Most of the power driving the clutch booster comes from the compressed air in the air tank; if the compressed air pressure leading to the booster is too low, it can cause insufficient assistance. Therefore, after such failures occur, the first step should be to check the compressed air pressure leading to the clutch booster.● Reasons for Heavy Pedal: Insufficient LubricationThe truck's clutch is driven by the booster cylinder (commonly known as the slave cylinder) through a series of mechanical structures to complete the separation of the pressure plate. There are several points within this structure that require lubrication. Insufficient lubrication can lead to excessive friction, which will result in a heavy clutch pedal.
For example, the clutch release fork shaft of certain vehicle models is located inside the flywheel casing, so it can only be connected to the transmission flywheel casing via a soft hose. However, many times we neglect the existence of this lubrication point when adding grease, resulting in excessive friction on the fork shaft, leading to a heavy pedal feel, and it may even cause excessive load on the fork that could lead to fatigue and breakage.● Reason for heavy pedal: the release bearing is too tight.
The clutch achieves its disengagement function by the pressing and releasing of the clutch plate through the pressure plate, and the pressing and releasing of the pressure plate is accomplished through the operation of the release fork driving the release bearing. The release bearing slides back and forth over the guide sleeve of the gearbox input shaft cap to control the disengagement of the pressure plate. If the clearance between the release bearing and the guide sleeve is too small, it will cause excessive friction, wasting drive force on the friction between the release bearing and the guide sleeve, leading to a heavy pedal feel that is unavoidable.● PostscriptThe above-mentioned faults that cause a heavy clutch pedal are relatively common, but the reasons for the heaviness are far from limited to just these. The entire clutch system relies on all components working together perfectly to function properly; any issue in one link could trigger a chain reaction. Therefore, if you encounter such problems, be sure to check from multiple perspectives to prevent unnecessary repairs and losses.
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