EDGE-CUTTING 1073362 - Caterpillar

How The Caterpillar BrakeSaver Works
As a truck descends a grade and ground speed increases, the drive wheels transfer vehicle ground speed through the drive train to the engine and the BrakeSaver rotor which is connected to the crankshaft. When the BrakeSaver retarder is activated, engine oil is directed to the rotor cavity by the oil control valve. Oil within the rotor cavity is then forced by the spinning rotor to flow across the fixed stator and BrakeSaver housing. As the oil flows, it is sheared by the spinning rotor vanes. This shearing slows the spinning rotor which, in turn through the drive train, slows the vehicle. The heat generated by this energy transfer is absorbed by the oil as the vehicle speed is slowed.
The amount of retarding is determined by two factors: 1) rotor speed, and 2) the amount of oil circulating in the rotor cavity. By varying these two factors, the drive can adjust the retarding level to match braking requirements on all types of grades and road conditions.
Rotor Speed
Since the ground speed of a descending vehicle is transferred through the drive train to the rotor, retarding can be increased or decreased by shifting transmission gears. Shifting should be done prior to encountering the grade. Maximum retarding is achieved at 2300 engine rpm. Remember, during BrakeSaver retarder operation any Caterpillar 3406 Truck Engine can operate up to this rpm regardless of rated rpm. As the engine speed is decreased, the amount of retarding available decreases! DO NOT exceed 2300 rpm.
Oil Flow
The hand control valve determines the amount of oil flowing to provide the desired amount of retarding. The BrakeSaver system has an infinite number of settings based on control lever position and engine rpm.
Engagement Delay
Frequently new owners of BrakeSaver hydraulic retarders also ask about the momentary delay that occurs before the BrakeSaver retarder engages. This two second engagement delay is actually a BrakeSaver retarder design feature that smooths engagement and accommodates gear shifting during "automatic" mode.
Driver Operational Checks
There are two quick operational checks you can make to determine if the BrakeSaver system is operating correctly.
1. To check retarding horsepower:a. Place transmission in neutral.b. Run engine to high idle rpm.c. Fully engage BrakeSaver hydraulic retarder.d. Engine rpm should drop approximately 125 25 rpm on 2100 rpm rated engines - the rpm drop will be lower for engines with 1900, 1800 or 1600 rpm settings.
This test should be limited to no more than 15 seconds followed by a 5 minute cool down between applications to prevent cooling system overheating.
2. To check free movement of control valve spool:a. Start the engine and run until system air pressure is at maximum.b. Shut off engine and engage BrakeSaver retarder before the air pressure drops below 520 kPa (75 psi).c. Disengage the BrakeSaver retarder and listen for a "klunk" sound. This "klunk" sound is the control valve hitting the control valve end cover. This confirms that the control valve is free, the control spring is operating normally and that air is venting