2000/08/14 Caterpillar

Wheel Loaders:

938G (PIN: 4YS1-690; 6WS1-1745; 8RS1-188; 9HS1-226)

950G (PIN: 2JS1-732; 4BS1-426; 3JW1-734; 5FW1-986; 5MW1-356; 8JW1-279)

962G (PIN: 3BS1-473; 5AS1-276; 4PW1-262; 6EW1-248; 6HW1-245; 7BW1-453)

Integrated Toolcarriers:

IT38G (PIN: 7BS1-539; 1CW1-353)

IT62G (PIN: 6PS1-376)

Service Magazine SEPD0466, 12 April 1999, "New Relief Valve for Gear Motor (Fan Drive) Improves Fan Speed Accuracy". Disregard this article. Refer to the article that follows.

Description of Change: A new relief valve is used on the gear motor (fan drive). The pressure setting of the relief valve maintains the correct fan speed at high engine speeds. The pressure setting of the new relief valve can be adjusted by turning an external screw. The pressure setting of the former relief valves is not adjustable. The design change will simplify the pressure adjustments that set the correct fan speed.

Illustration 1	g00689313
(1) 159-7986 Gear Motor. (2) Relief valve.

Adaptable To:

Illustration 2	g00689027
Typical Relief Valve Location (3) 139-6083148-6742 Gear Motors. (4) Relief valve.

Note: Refer to Illustrations 1 and 2 in order to identify the respective gear motors and the location of the relief valve. Refer to Table 1 in order to cross reference between the machine models, part numbers of the gear motors and relief valves, and pressure setting of the new relief valves.

Installation Procedure

1. Install an 8J-2413 O-Ring Seal onto the new relief valve.

2. Install the new relief valve into the gear motor.

3. Tighten the relief valve to a torque of 61 ± 4 N·m (45 ± 3 lb ft).

Note: Make sure that the relief valve is adjusted to the proper pressure. If the relief valve is not adjusted to the proper pressure, damage to the hydraulic system components may occur.

Show/hide table

NOTICE
Component damage can occur if the pressure setting is not correct.

Table 1

Relief Valves for Gear Motors
Models	Gear Motor	New Relief Valve	Pressure Setting	Former Gear Motor	Former Relief Valve	Pressure Setting
938G (PIN: 4YS1-188; 6WS; 8RS1-187; 9HS)	159-7986	159-4019	13000 kPa (1885 psi)	148-6742	149-6059 - 17000 kPa (2450 psi) 161-3996 - 13500 kPa (1950 psi) 165-6085 - 13000 kPa (1885 psi)
938G (PIN: 4YS189-UP; 8RS188-UP)	159-7986	159-4019	12000 kPa (1740 psi)		143-4517	11000 kPa (1600 psi)
950G (PIN: 2JS; 4BS; 3JW; 5FW; 5MW; 8JW)	159-7986	159-4019	13000 kPa (1885 psi)	139-6083	149-6059 - 17000 kPa (2450 psi) 161-3996 - 13500 kPa (1950 psi) 165-6085 - 13000 kPa (1885 psi)
962G (PIN: 3BS; 5AS; 4PW; 6EW; 6HW; 7BW)	159-7986	159-4019	13000 kPa (1885 psi)	139-6083	149-6059 - 17000 kPa (2450 psi) 161-3996 - 13500 kPa (1950 psi) 165-6085 - 13000 kPa (1885 psi)
IT38G (PIN: 1CW; 7BS)	159-7986	159-4019	13000 kPa (1885 psi)	139-6083	149-6059 - 17000 kPa (2450 psi) 161-3996 - 13500 kPa (1950 psi) 165-6085 - 13000 kPa (1885 psi)
IT62G (PIN: 6PS)	159-7986	159-4019	13000 kPa (1885 psi)	139-6083	149-6059 - 17000 kPa (2450 psi) 161-3996 - 13500 kPa (1950 psi) 165-6085 - 13000 kPa (1885 psi)