Damage To Hydraulic Hoses On Lift Circuit Caterpillar

Damage To Hydraulic Hoses On Lift Circuit

Usage:

TRACK-TYPE TRACTORSD8H (22A1-UP, 35A1-UP, 36A1-UP, 46A1-UP, 52A1-UP, 68A1-UP),
D8K (66V1-UP, 76V1-UP, 77V1-UP) TRACK-TYPE TRACTORS

Reference: Service Magazine; SEBD1134; September 7, 1981; "Modification Of Yoke Prevents Possible Wear Or Damage To Hydraulic Lines".

Problem:

Failure to maintain the bearings in the crosstube and the lift cylinder trunnion can lead to fraying and wear on the hydraulic hoses that run from the crosstube to the lift cylinder. If the hoses are damaged, high pressure oil can be sprayed onto the hot components of the engine or the operator, causing a fire, serious injury or death.

The hydraulic hose assemblies that connect to the lift cylinders should be inspected for damage where they pass under the hood. If the hoses are damaged by contact with the hood, a repair should be made before the machine is operated. This contact can occur when the tube mounted on the lift cylinder contacts the yoke or crosstube. This contact can cause the tube to be bent upward causing the hoses to contact the underside of the hood. Serious injuries can occur if a hose bursts and sprays hot hydraulic oil onto the hot components of the engine or the operator.

The tube assembly can contact the yoke and crosstube when the bearings in the crosstube and trunnion are worn, allowing excessive movement of the tube assembly that is mounted to the lift cylinder. The service life of the bearings on the D8K may be shorter if the yoke is not modified as shown in the reference article (attached).

Solution:

The problem can be prevented by replacing the worn bearings in each end of the crosstube and the bearings in the trunnion of lift cylinder (3). Lift cylinder tube assembly (2) should be replaced if it is bent and causing hoses (4) to move from the horizontal plane and contact hood (1). Refer to Illustration 1.

The hose assemblies should be replaced if the hose is frayed. A frayed hose can be weakened as the contact wears into the steel reinforcement layers or as moisture causes the steel reinforcement to corrode. The yoke should be checked to see if rework of the yoke is needed. If rework is needed, refer to attached reference article.

NOTE: Customers and operators should be cautioned that the daily inspection is an important part of machine maintenance and operation. They should be looking for frayed and leaking hoses each day and making repairs when they find a problem.

Illustration 1.