HOSE A 0305947 - Caterpillar

Table 1
Required Tools    
Part Number     Description     Required Amount    
6V-3121     Multitach     1    This test will determine the following items.
The test will measure the performance of the tractor engine.
If equipped, the test will determine if the retarder operates correctly.
If equipped, the test will determine if the pressures (air and oil) for the retarder are correct.Note: For this test, the oil must be at normal operating temperature.Procedure
Illustration 1 g00288554
Location Of The Retarder Lever
Install the 6V-3121 Multitach on the engine. The 6V-3121 Multitach can measure engine speed by the use of a photo pickup and reflective tape. The multitach also uses a magnetic pickup or a tachometer generator. Refer to Special Instruction, SEHS7807 for the use of the multitach. Start the engine.
When the shift lever is in the NEUTRAL position, be sure that the HIGH IDLE rpm is correct. Also, make sure that the SET POINT rpm is correct. Refer to the microfiche for the fuel settings and related information.
To ensure that the transmission oil does not overheat do not keep the torque converter in the stall condition for more than 30 seconds. After the torque converter stall test allow the transmission oil to cool before stopping the engine.
With the engine at HIGH IDLE rpm, place the retarder control lever to the FULLY ACTIVATED position (pull toward the operator). The engine rpm must be 2000 50 rpm for the 621F and 623F Wheel Tractor-Scrapers. The rpm must be 1875 75 rpm for the 627F Wheel Tractor-Scrapers .
Push the retarder control lever back to the RELEASED position. The engine rpm must go back to HIGH IDLE rpm.Results
If the retarder lever is engaged and the engine rpm is too high, then one of the following items may be the problem.
Illustration 2 g00495386
Location of the retarder air control valve
There is no air pressure to the supply passage of the retarder air control valve. The retarder air control valve is located on the steering column.
There is wear or damage to the retarder air control valve. This allows little air pressure to flow to the air pressure regulator.
There is wear, damage or an incorrect adjustment to the air pressure regulator.
The hydraulic system has a failure.If the retarder lever is released and the engine rpm is too low, then one of the following items may be the cause.
There is wear, damage or an incorrect adjustment to the air pressure regulator.
There is wear or damage to the retarder air control valve. This will slow the release of pressure air from the delivery passage. This may even stop the release of pressure air.
The hydraulic system has a failure.Note: For more information on the retarder air system, refer to Systems Operation/Testing and Adjusting, SENR6819, "Air System & Brakes for 621F, 623F, & 627F Wheel Tractor-Scrapers" .