TRANSMISSION AR 3175322 - Caterpillar

Personal injury can result from removing hoses or fittings in a system under pressure.Failure to relieve pressure can cause personal injury.Do not remove or disconnect hoses or fittings until all pressure in the hydraulic system has been relieved.
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids.Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat® products.Dispose of all fluids according to local regulations and mandates.
Reference: Refer to Testing and Adjusting, "Machine Preparation" before you begin this procedure.Introduction
The following test procedure will verify whether the pressure setting for the pilot pressure is within the specified limit. The following adjustment procedure will explain the procedure for adjusting the pilot pressure.Specifications
Table 1
Pilot Pressure
Description Specification Actual
Pilot Pressure 4000 200 kPa (580 29 psi) Required Tools
Illustration 1 g02109937
Tooling (A)
Illustration 2 g01623868
Tooling (B)
Table 2
Tool Item Part Number Description Qty
A A1 8T-0855 Pressure Gauge (0 to 4,000 kPa (0 to 580 psi)) 1
A1 8T-0857 Pressure Gauge (0 to 10,000 kPa (0 to 1,450 psi)) 1
A2 6V-3989 Fitting 1
A3 6V-4143 Quick Connect Coupler 2
A4 177-7861 Hose As (4.3 m (14 ft)) 1
B 198-4240 Digital Pressure Indicator Gp
B1 198-4234 Digital Indicator 1
B2 198-4239 Pressure Sensor Gp (0 to 41,368 kPa (0 to 6000 psi)) 1
B3 198-4236 Adapter Cable As 1 Note: Tooling (A) or Tooling (B) may be used to perform these tests.Test Preparation
Move the machine to a smooth horizontal location.
Chock the wheels.
Lower all of the implements.
Illustration 3 g03601657
(1) Pressure test port for pilot pressure
(2) Pressure reducing valve
(3) Locknut
(4) Adjustment screw for pressure reducing valve (pilot pressure)
Remove the dust cap on test port (1).
Attach Tooling (A) to test port (1). Pressure test port (1) will indicate the oil pressure in the pilot system for the implements. Pressure reducing valve (2) limits the pilot system for the implements. Pressure reducing valve (2) will close when the pilot system reaches the pilot pressure. Test Procedure
Start the engine.
In order to test the pilot pressure, run this test with hydraulic oil at 60° 5°C (140° 9°F).
Stall the blade tip cylinder.
Operate the engine at high idle. Throttle to 2150 rpm
Check that pump discharge pressure is 10,000 kPa (1450 psi) or higher.
Record the pilot pressure at test port (1). Pilot pressure should be 4000 200 kPa (580 29 psi).
If the pressure at Tooling (A) is within the specified limit, the test is complete. Adjustment Procedure
In order to adjust the pilot pressure, run this test with hydraulic oil at 60° 5°C (140° 9°F).
If the pressure reading is incorrect, loosen locknut (3) on adjustment screw (4). Turn the adjustment screw clockwise in order to increase the setting. Turn the adjustment screw counterclockwise in order to decrease the