Transmissions play a fundamental role in the process of moving a vehicle. A car’s transmission is connected to the engine and serves to transmit’ the power generated there to the wheels that drive it. Within this, gears reduce the number of revolutions of a crankshaft, ensuring more effective use of the engine’s torque.
When a car is in neutral power from the engine is driving the transmission input shaft, in turn rotating some parts in the transmission on idle. However, once first gear is selected to go forwards or reverse to go backwards, the clutch is depressed, disengaging the input shaft from the engine. Due to inertia, the input shaft could still spin for some time however, meaning certain parts of the transmission will be spinning too fast to interlock with the gears.
A clutch brake works by fixing to the input shaft on a manual gearbox, acting as a source of friction between the release bearing and transmission bearing retainer cap, reducing the input shaft’s rate of rotation and slowing the spinning inside the gearbox. This allows for the gears to ‘mesh’ effectively without any significant grinding or clashing. Clutch brakes are instrumental in avoiding excessive wear of those all-important inner transmission components.
There are three common types of clutch brake found in vehicles: a one-piece clutch brake, a two-piece ‘hinged’ clutch brake and a torque. limiting clutch brake. The one-piece variety can only be installed with the transmission removed from the vehicle, so it can go over the circular input shaft. Its thick plate provides a good friction surface to slow the input shaft when it’s spinning. A two-piece hinged clutch brake on the other hand, can be installed with the transmission in place by hinging and then fixing around the input shaft. Finally, a torque-limiting clutch brake is used for more heavy-duty applications and features a hub with washers that slip under a certain amount of torque, ensuring the smooth engagement of gears in the transmission.