ISM, ISMe, and QSM11 – 001-039   Idler Gear, Hydraulic Pump

• Remove the gear cover. Refer to Procedure 001-031 in Section 1.

Three idler gear assemblies are used:

• Water pump idler gear (1)
• Camshaft idler gear (2)
• Hydraulic pump idler gear (3).

SAE ‘A’ and SAE ‘B’ Removal

To remove the hydraulic drive idler gear assembly, remove:

• Mounting spacer (1)
• Rectangular seal (2)
• The three twelve-point capscrews
• Gear retainer (3)
• Rectangular seal (4)
• Front thrust bearing (5)
• Idler gear (6)
• Rear thrust bearing (7)
• Idler gear shaft (8).

NOTE: SAE “A” drives do not use a rectangular seal (4) on the rear surface of the gear retainer.

SAE ‘B-B’ Removal

To remove SAE B-B hydraulic drive idler gear assembly, remove:

• Mounting Spacer (1)
• Tapered Roller Bearing (2)
• Gear Drive (3)
• Tapered Roller Bearing (4)
• Shim(s) (5)
• Idler Gear Shaft (6)
• Mounting Spacer (7)
• Rectangular Seal (8).

Mark or tag the individual pieces of the idler gear assembly and attach them together.

WARNING  When using solvents, acids or alkaline materials for cleaning, follow the manufacturer’s recommendations for use. Wear goggles and protective clothing to reduce the possibility of personal injury.

WARNING  Wear appropriate eye and face protection when using compressed air. Flying debris and dirt can cause personal injury.

Clean the parts with solvent. Dry with compressed air.

WARNING  Wear appropriate eye and face protection when using compressed air. Flying debris and dirt can cause personal injury.

Use a bristle brush to clean the oil drillings in the idler gear shaft.

Blow out the oil drillings with compressed air.

Use a straightedge to inspect the retaining capscrews for necking. If necking is observed, do not reuse the capscrews. They must be replaced.

Inspect the idler gear for chipped, broken, or cracked teeth.

NOTE: Measurements do not apply to SAE ‘B-B’ hydraulic drive idler gear. Visually inspect the inside diameter of the gear for reuse.

Measure the inside diameter of the idler gear bushing bore.

SAE ‘A’ and ‘B’ Hydraulic Drive Idler Gear Bushing Bore Inside Diameter

Measure the outside diameter of the idler gear shaft.

SAE ‘A’ and ‘B’ Hydraulic Drive Idler Gear shaft Outside Diameter

SAE ‘B-B’ Hydraulic Drive Idler Gear Shafts Outside Diameter

Measure the outside diameter of the ring dowel.

Hydraulic Drive Idler Ring Dowel Outside Diameter

NOTE: SAE ‘B-B’ hydraulic drive gear assembly does not use thrust washers.

Measure the thrust washer thickness in three places 120-degrees apart.

Hydraulic Drive Idler Thrust Washer Thickness

NOTE: SAE ‘B-B’ hydraulic drive gear assembly does not use thrust washers.

Flex the thrust washers approximately 3 to 6 mm [1/8 to 1/4 in], and inspect the surfaces for cracks.

CAUTION  The grooved side of the rear thrust bearing must be facing toward the gear to prevent damage to the gear and engine during engine operation.

SAE ‘A’ and SAE ‘B’ Install

Use Lubriplate™ 105, or equivalent, to lubricate the thrust bearings and idler gear.

Install the idler gear shaft (8) and rear thrust bearing (7).

NOTE: When an SAE B drive is used, a special hydraulic drive idler shaft with two oil holes is used. With the engine in the upright position, orientate the shaft so that one oil hole is at twelve- o’clock and the other at four-o’clock.

CAUTION  The grooved side of the front thrust bearing must be facing toward the gear to prevent damage to the gear and engine during engine operation.

Install the idler gear (6) and front thrust bearing (5).

NOTE: On SAE “B” drives, install a new rectangular seal on the rear surface of the gear retainer (4) before installing the retainer.

Install the gear retainer (4).

Install the three retaining capscrews and tighten.

SAE ‘B-B’ Install

NOTE: Use shim(s) as necessary for proper idler gear end clearance.

Use Lubriplate™ 105, or equivalent to lubricate the roller bearings and gear.

To install SAE B-B hydraulic drive idler gear assembly, install

• Mounting Spacer (1)
• Tapered Roller Bearing (2)
• Gear Drive (3)
• Tapered Roller Bearing (4)
• Shim (s) (5)
• Idler Gear Shaft (6)
• Mounting Spacer (7)
• Rectangular Seal (8).

The following idler gear end clearance and backlash checks apply to all three idler gears. The same MINIMUM and MAXIMUM values apply, also.

Use a dial indicator gauge with a magnetic base to measure the idler gear end clearance.

Place the contact tip of the gauge against the face of the idler gear.

Idler Gear End Clearance

Use a dial indicator gauge with a magnetic base to measure the idler gear backlash.

Place the contact tip of the gauge against a tooth on the idler gear.

Do not allow the mating gears to move while measuring the backlash.

Idler Gear Backlash

• Install the gear cover. Refer to Procedure 001-031 in Section 1.
• Operate the engine to normal operating temperature and check for leaks.