GEAR-RING 6Y1278 - Caterpillar

Table 1
Required Tools
Part Number Part Description Qty
177-7861 Hose As 1
6V-4143 Couplers 2
8T-0856 Pressure Gauge (0 kPa to 6,000 kPa (0 psi to 870 psi)) 1
Personal injury or death can result from escaping fluid under pressure.Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue and cause serious injury and possible death. If fluid is injected into your skin, it must be treated by a doctor familiar with this type of injury.Always use a board or cardboard when checking for a leak.
Hot oil and components can cause personal injury.Do not allow hot oil or components to contact skin.
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.
Move the machine to a hard, level surface.
Engage the parking brake and stop the engine.
Illustration 1 g06031676
Pilot oil filter
(1) Pressure tap (pilot oil pressure)
Connect a 177-7861 Hose As and an 8T-0856 Pressure Gauge to pressure tap (1).
Start and run the engine at low idle rpm. With the oil at normal operating temperature, the pressure should read 3170 170 kPa (460 25 psi).
If the pressure is not correct, stop the engine.
Depress the service brake pedal at least 80 times to release any pressure in the brake accumulators.
Move the joystick control lever several times through the full range of travel to release any pressure in the implement pilot circuits.
Move the steering control several times in both directions to release any pressure in the steering system.
Press and hold the breaker relief valve to release any pressure in the hydraulic tank.
Illustration 2 g01138918
Remove fire wall (2).
Illustration 3 g06031683
(3) Pilot relief valve
Illustration 4 g01138921
(3) Pilot relief valve
(4) Locknut
(5) Adjusting screw
Loosen locknut (4) and turn adjusting screw (5) on pilot oil pressure reducing valve (3). Turn adjusting screw (5) clockwise to increase pressure and counterclockwise to decrease pressure. The correct pressure is 3170 170 kPa (460 25 psi).
Repeat Step 4.
If the pressure reading is correct, stop the engine. Remove the test equipment from pressure tap (1). Place the protective cover over the pressure tap.
If the pressure reading is not correct, stop the engine. Repeat Steps 6 through 12.
Illustration 5 g01138918
Install fire wall (2).