Gear Pump For The Brake, Pilot And Steering System May Have Failures To Front Bearing Or Front Shaft Caterpillar


Gear Pump For The Brake, Pilot And Steering System May Have Failures To Front Bearing Or Front Shaft

Usage:

EXCAVATORSM312 (6TL),
M315 (7ML),
M318 (8AL, 6ES, 8SS),
M320 (6WL, 9PS) EXCAVATORS

Problem:

The hydraulic gear pump on the listed excavators may experience failure of the front bearing or the front shaft. The failures result in the disabling of all hydraulics due to the lack of pilot oil pressure.

Solution:

Until a permanent solution can be determined, follow the following options according to the PIN ranges identified below.

OPTION A
M312 (6TL1-377), M315 (7ML1-772)

There is no third point on the engine to mount a new pump support. Replace the front bearing and the adapter plus reuse the same pump if it is still operational. If the pump is not working, order a new 117-8031 Gear Pump Group. The suggested replacement bearing is a higher capacity bearing and will provide increased service life.

Procedure:

1. Remove and discard the existing 125-6227 Bearing and the 144-6248 Connector on the front of the pump. If the gear pump or its front shaft is damaged, order a new 117-8031 Gear Pump Group (1)

OR

2. If the pump is not damaged, reuse the pump. In both cases, replace the 125-6227 Bearing (front) and 144-6248 Connector Sleeve of the pump.
3. Remove the existing 123-0864 Adapter, one 3E-4988 Lockwasher and four 6V-5196 Bolts.
4. Install 153-2902 Bearing (4) (includes connector), 147-1847 Adapter Plate (5), 7W-1165 Gasket (3), and 7I-8935 Bolts (2).

NOTE: If there is any damage to the pilot pump pinion or the shaft in the timing case, replace pump drive gear (6). Remove damaged gear and the 125-6616 Woodruff Key. Install new 7W-1220 Gear (6) and apply Loctite 262 to the threads of the front shaft. Install 7W-1219 Nut (7) and tighten the nut to 65 N·m (48 lb ft). DO NOT re-install the 125-6616 Woodruff Key on the shaft.

NOTE: Make sure the engine oil is not contaminated by pinion debris. If the oil is contaminated, flush and refill the engine oil system.

OPTION B
M312 (6TL378-634) M315 (7ML773-1214)

The engine block for the above PIN ranges will allow the installation of the new 145-4099 Plates Assembly. Order and install the following parts.

Procedure:

1. Remove the existing pilot pump and pilot pump support.
2. Mount the new 145-4099 Plates Assembly (support) (15) without fastening the 145-4096 Plate (14) to the support. Use bolt (13) with one washer (11). Use bolts (16) with four washers (11) between the plate assembly and the engine.
3. Mount the new 168-6800 Pump Group (8) on the engine on the existing 148-7147 Drive Group (not serviced).
4. Install the 145-4096 Plate (14) to the plates assembly with bolt (12) and one washer (11). Fasten the plate (14) to the pump with washers (9) and locknuts (10). Use the hole adjustment slots in plate (14) and in plates assembly (15) to eliminate any preload or displacement of the pump at final assembly.
5. Finish tightening all fasteners to their specifications.

NOTE: If there is any damage to the pilot pump pinion or the shaft in the timing case, replace pump drive gear (6). Remove damaged gear and the 125-6616 Woodruff Key. Install new 7W-1220 Gear (6) and apply Loctite 262 to the threads of the front shaft. Install 7W-1219 Nut (7) and tighten the nut to 65 N·m (48 lb ft). DO NOT re-install the 125-6616 Woodruff Key on the shaft.

NOTE: Make sure the engine oil is not contaminated by pinion debris. If the oil is contaminated, flush and refill the engine oil system.

OPTION C
M318 (M318 (8AL, 6ES, 8SS), M320 (6WL, 9PS)

There are no reports of failed bearings on the above machines at this date. There are only reports of sheared front shafts (part of 153-2666 Bearing).

NOTE: If there is any damage to the pilot pump pinion or the shaft in the timing case, replace 7C-1782 Pump Drive Gear (17). Install new gear (17). Apply Loctite 262 to the threads of gear (17) and install 171-2989 Locknut (18). Tighten locknut (18) to 65 N·m (48 lb ft). DO NOT re-install the 125-6616 Key on the shaft.

NOTE: Make sure the engine oil is not contaminated by pinion debris. If the oil is contaminated, flush and refill the engine oil system.

COPYRIGHT 1999 CATERPILLAR ALL RIGHTS RESERVED

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