PISTON AS 2356891 - Caterpillar

Illustration 1 g00290369
(1) Torque for switch ... 68 10 N m (50 7 lb ft) (2) Shim thickness: 7B-8451 Shim ... 0.25 mm (.010 inch) 119-9738 Shim ... 0.13 mm (.005 inch) (3) Torque for valves ... 28 7 N m (21 5 lb ft) (5) Cap (6) Quick coupler nippleReference: Systems Operation/Testing and Adjusting, RENR1778, "Track - Tension/Detension".Note: Leave bolts (7) loose prior to tightening locknuts (8) on strap (9) . (10) 107-6328 Accumulator Assembly precharge pressure ... 10300 kPa (1500 psi)Note: Refer to Systems Operation, Testing and Adjusting, RENR1778, "Track - Tension/Detension" for the procedure to check the Nitrogen charge in the accumulator.Procedure to Calibrate the Warning Switch for the Tensioner
The warning switch for the tensioner must be calibrated after replacement. Use the following procedure to recalibrate the switch.
Table 1
Tools Needed    
Part Number    Description    
1U-9058     Hose Assembly    
8T-0500     Continuity Tester    
Illustration 2 g00290670
Install new switch (1). Reuse shims (2) which were removed from the former switch.
Connect a circuit continuity tester between the switch leads. The circuit should be open.
Open valve (3) from one-half to one turn. Connect the charging hose. Make sure that the needle valve on the charging hose is closed.
Start the engine. Run the engine at low idle.
Actuate the implement hydraulic circuit in order to pressurize the charging hose.
Open the needle valve and allow the tensioner to fill for at least 10 seconds. The tensioner should be charged. The continuity tester should indicate a closed circuit. If the circuit does not close, proceed to Step 15.
Close the needle valve on the charging hose.
Place the implement control lever in the FLOAT position.
Locate the needle valve that is on the charging hose. Slightly open the needle valve until there is a very slow amount of purging of hydraulic pressure from the tensioner.
Record the pressure reading when the continuity tester indicates that the switch circuit has opened.
Repeat Steps 5 through 10 two additional times. Observe the system and record the pressures.
Average the three pressure readings. The average pressure should be above 10340 kPa (1500 psi).
If the average pressure is below 10340 kPa (1500 psi), remove switch (1) and add a 7B-8451 Shim (0.25 mm (.010 inch)).
Repeat Steps 5 through 12 until the average pressure is above 10340 kPa (1500 psi).
If the circuit does not close with the tensioner at the full pressure, remove switch (1) and remove a 7B-8451 Shim (0.25 mm (.010 inch)).Note: Add or remove only one shim at a time. If it is not possible to achieve the specified conditions by using 0.25 mm (.010 inch) shims, use a 119-9738 Shim (0.13 mm (.005 inch) shim). The 0.13 mm (.005 inch) shim will provide a finer adjustment.
If the switch cannot be satisfactorily calibrated, replace 7S-9847 Conical Washers (4). The conical washers (4) are Belleville washers. Repeat the calibration procedure.