TUBE AS 1166211 - Caterpillar

Table 1
Required Tools    
Part Number     Description     Quantity    
9U-7400     Multitach Tool Group     1    This test will determine the following conditions:
The engine performance is good.
The retarder engages properly.
The retarder releases properly.
The retarder air pressure is good.
The retarder oil pressure is good.Procedure
Illustration 1 g00420584
9U-7400 Multitach Tool Group
Illustration 2 g00699469
Location of Retarder Control Lever
Install 9U-7400 Multitach Tool Group on the scraper engine. 9U-7400 Multitach Tool Group can measure engine speed by the use of the photo pickup and reflective tape, a magnetic pickup or a tachometer generator. Instructions for the use of 9U-7400 Multitach Tool Group is in the case. Start the scraper engine.
During this test, the tractor engine is OFF. Make sure that the air pressure is at a normal operating pressure.
While the transmission control lever is in the NEUTRAL position, make sure that the HIGH IDLE rpm is correct. Also, make sure that the SET POINT rpm is correct.
Be sure that the torque converter (transmission) oil does not get too hot.
With the scraper engine at HIGH IDLE rpm, pull the retarder control lever to the FULLY ACTIVATED position. The engine rpm must be 1550 100 rpm.
Push the retarder control lever back to the RELEASED position. The engine rpm must return to HIGH IDLE rpm.
Stop the scraper engine.ResultsWhen the retarder control lever is FULLY ACTIVATED and the engine rpm is too high, one of the following conditions occurred:
Unavailable air pressure to the supply passage of the retarder air control valve
The retarder air control valve is worn or the retarder air control valve is damaged. This will allow little air pressure or no air pressure to flow to the air pressure regulator.
There is wear, damage or incorrect adjustment of the air pressure regulator.
The hydraulic system has a failure.When the retarder control lever is in the RELEASED position and the engine rpm is too low, one of the following conditions occurred:
Wear, damage or incorrect adjustment of the air pressure regulator
Wear to the retarder air control valve or damage to the retarder air control valve prevents the release of pressure air from the delivery passage.
Wear to the retarder air control valve or damage to the retarder air control valve slows the release of pressure air from the delivery passage.
The hydraulic system has a failure.Note: For more information on the retarder air system, refer to the Systems Operation, Testing and Adjusting, "Air System and Brakes".