Transmission Shaft Welds May Fail on Certain Motor Graders{3063, 3155, 3170} Caterpillar

Motor Grader:

120K (S/N: SZN374-UP; JAP1777-UP)

120M Series 2 (S/N: M9C242-UP; M9H201-UP; R9N102-UP)

120M (S/N: R9A126-UP; B9C1141-UP; R9C1-UP; D9W419-UP)

12K (S/N: JJA521-UP; SZP156-UP)

12M Series 2 (S/N: F9B103-UP; F9M133-UP; R9P1-UP; R9S1-UP)

12M (S/N: R9B1-UP; B9F1442-UP; B9R1388-UP)

140K (S/N: JPA1587-UP; SZL366-UP)

140M Series 2 (S/N: M9D500-UP; R9G1-UP; R9M1-UP)

140M (S/N: B9D4002-UP; D9G1300-UP)

160K (S/N: SZM221-UP; JBP152-UP)

160M Series 2 (S/N: M9E409-UP; M9K425-UP; R9L101-UP; R9T1-UP)

160M (S/N: B9E848-UP; D9T300-UP)

Introduction

The problem with the welding machine has been identified and corrected.

Problem

Illustration 1	g03341329
(1) Shaft number two (2) Shaft number three (3) Shaft number four

Loss of forward or reverse gears could be caused by a failure of transmission shaft number 2 (1), shaft number 3 (2), or shaft number 4 (3). The failure occurs where the gear is welded to the shaft. The loss of forward or reverse gears requires first checking the transmission clutch pressures and checking the screens for any debris. Failure of the weld is identified by a loss of clutch pressure and/or metal in the transmission sump screen.

Illustration 2	g03341395
Photo of a failed shaft

Any issue with the welded shaft would be expected to propagate under 1,000 hours of operation.

Solution

Replace shaft assembly with current stock parts. Follow Disassembly and Assembly Manual for your machine regarding repair instructions.