WRENCH-SPANNER 1766538 - Caterpillar

Introduction
For Specifications with illustrations, make reference to the Specifications For 769D & 771D Truck, Suspension Cylinders, SENR8617. If the Specifications in SENR8617 is not the same as in the Systems Operation, Testing & Adjusting, look at the printing date on the front cover of each module. Use the Specifications given in the module with the latest date.Front Suspension Cylinders
Each front wheel is held by a suspension cylinder, which is an oil-pneumatic hydraulic cylinder. These cylinders are the kingpins for the steering linkage. The cylinders also provide the "spring action" and shock absorber action of the front suspension. The frame mounting for the front suspension cylinders is set with a slight inclination angle to provide correct steering operation.The main components of the suspension cylinder are a cylinder and a rod. The cylinder is fastened to the frame of the machine. As the wheel moves up and down, the rod is free to move up and down inside of the housing.Rod Moves Up
Front Suspension Cylinder Operation
(1) Cylinder. (2) Chamber [for nitrogen]. (3) Rod. (4) Orifices [two]. (5) Ball check. (6) Cavity. (AA) Nitrogen. (LL) Oil.The control of the shock load felt by the front wheels is done by controlling the rate of oil flow through orifices (4) and ball check (5) from chamber (2) to cavity (6).When a shock load is felt, the wheel is moved up which causes rod (3) to move up in the housing. The movement of rod (3) compresses the nitrogen in chamber (2). Oil flows from chamber (2) to cavity (6) through orifices (4) and ball check (5).Rod Moves Down
Front Suspension Cylinder Operation
(1) Cylinder. (2) Chamber [for nitrogen]. (3) Rod. (4) Orifices [two]. (5) Ball check. (6) Cavity. (AA) Nitrogen. (LL) Oil.As the shock load diminishes, the action of the suspension cylinder is reversed. The weight of the wheel and axle plus the pressure of the nitrogen in chamber (2) moves rod (3) out of the housing. As rod (3) moves down, the oil volume of cavity (6) decreases and the oil is put under pressure. The flow of oil closes ball check (5) and oil pressure keeps it closed. The oil must flow out through orifices (4) to chamber (2).As rod (3) moves down, the lower orifice is closed and the amount of oil that goes to chamber (2) is decreased. The other orifice is slowly closed off as rod (3) moves down. This again decreases the amount of oil that goes to chamber (2). The orifice slowly being closed prevents rod (3) from hitting the bottom of the housing with a shock.Rear Suspension Cylinders
Two oil-pneumatic hydraulic cylinders are fastened between supports on the rear of the machine frame and the axle housing. The location of each suspension cylinder is directly behind and in line with each side rail of the frame. A support, which is fastened to the front side of the differential housing, is connected to the frame by a ball joint. The two suspension cylinders give the "spring action" between the