Question 61 MODE01 - Chief MODU Engineer

The Correct Answer is B **Explanation for Option B (Overheating because of slipping shoes):** The scenario describes a diesel engine equipped with an air bladder clutch unit that is **inadequately inflated**. The air bladder, when properly inflated, presses the clutch friction shoes firmly against the drum (or flywheel) to engage the power transmission. If the bladder is inadequately inflated, the clamping force applied by the shoes is insufficient. When an **additional load** is applied to the engine (and thus to the drivetrain), the required torque transmission through the clutch increases dramatically. Because the clamping force is too low, the clutch shoes will slip against the drum/flywheel rather than gripping firmly. This slipping action converts the mechanical energy into intense heat (friction) and causes rapid overheating of the clutch components (shoes, drum, and possibly the surrounding housing). **Why the Other Options are Incorrect:** * **A) pneumatic seizure:** "Pneumatic seizure" relates to a catastrophic failure, usually involving a complete lack of airflow or cooling, leading to extreme temperatures and physical locking in components like air compressors or sometimes engine cylinders. It is not a standard failure mode directly resulting from clutch slippage in an air bladder system. The primary immediate effect of insufficient pressure is slippage, not seizure. * **C) excessive wear on the thrust bearings:** Excessive wear on engine thrust bearings is typically caused by issues leading to high axial (fore-and-aft) loads, such as improper alignment, excessive belt tension, or issues within the power take-off (PTO) or gearbox transmitting that axial force back to the engine. While a failing clutch assembly could potentially transmit unusual forces, the immediate and dominant consequence of low pressure and slippage is localized heat and wear within the clutch itself, not high axial loading leading to thrust bearing failure. * **D) chipped reduction gear teeth:** Chipped gear teeth are almost always caused by mechanical shock loading, sudden engagement at high speeds (abusing the clutch), misalignment, or metal fatigue due to continuous overloading. While severe clutch slippage puts the transmission under strain, the slipping itself acts as a torque limiter, preventing the full shock load from instantly reaching the reduction gears. Overheating and wear in the clutch unit are the direct result, not immediate damage to the transmission gears.