Engine Brakes

Compression Brake ControlsOn older mechanically governed engines, severalswitches control the operation of the compressionrelease brake. The switches that are connected in inseries are: a dash switch for power, a swtitch forbraking level, fuel linkage/lever switch, a clutchswitch and a brake switch. The last switch, a brakeswitch is optional. This switch is more commonlyused on coaches to activate the engine brake whenthe service brakes are applied.typical inputs for control. A number of customerprogrammable strategies can be programmed. Forexample, the brake can be set-up to activate onlyabove a vehicle speed threshold, or to maintainvehicle speed when coasting down a grade.Remember the brake will not operate unless thedriver has their foot off the throttle and the clutchpedal is released.On electronically controlled engines, the ECMcontrols the braking. Inputs from brake, clutch,throttle position, idle validation switch, vehiclespeed sensor, ABS control are

Servicing Engine Brakes‣Clutch and fuel pump switches may requireadjustments to cause the brake to operate correctly.The on switch, clutch and fuel pump switch arewired in series so if any are open the brake will notoperate.‣Electronic controlled brakes may require aminimum road speed and engine rpm to enable thebrake.Tune-up kits areavailable for brakes andshould be included inregularlyscheduledengine maintenanceThe diagram belowillustrates “O” ringsthat are part of a tuneupkit.‣Slave pistons are adjusted when the valves forthat cylinder are being adjusted.Maladjustment is indicated when the brakeseffectiveness is diminished

Engine Brake Operation – PLN System

Caterpillar Engine Brake Operation (PLN)