611 and 615C Series II Wheel Tractor-Scrapers Steering System Caterpillar

When any test is performed on the steering system, the hydraulic oil must be at the normal operating temperature. Starting the engine, lifting the bowl or turning the machine will increase the oil temperature.

Problem

Hydraulic cylinder drift is present in the steering cylinders.

Probable Cause

• The seal on the cylinder piston is damaged.

• There is a scratch or a groove in the cylinder bore.

• There is a scratch or a groove on the cylinder rod.

• The seal in the cylinder head is damaged.

• There is dirt or damage in the steering valve.

• There is damage or a loose fitting in the hydraulic lines.

• There is dirt in the line relief valves.

• There is damage to the line relief valves.

Problem

The machine turns correctly while roading, but the machine turns slowly against a load.

Probable Cause

• There is oil leakage past the seat of the relief valve.

• There is oil leakage past the seals in the steering control valve.

• There is oil leakage past the ball in the ball check valve that is located in the steering control valve.

• The main control spool does not fit correctly in the bore of the steering control valve.

Problem

Turning the steering wheel is difficult.

Probable Cause

• The oil is cold.

• The steering column may bind due to a mechanical misalignment.

• The mechanical linkage in the steering control has restricted movement.

• The main control spool is sticking in the bore of the steering control valve.

Problem

The machine turns slowly in both directions.

Probable Cause

• The center position for the main control spool in the steering control valve is incorrect.

• The pressure setting for the relief valve is set too low or the relief valve has failed.

• The seals in the steering control valve have failed.

• The valve seat in the ball check valve is damaged.

• The main control spool in the steering control valve is damaged.

• The oil pressure from the hydraulic and steering vane pump is too low.

• The piston seals on the steering cylinders have failed.

Problem

The machine turns slowly in one direction.

Probable Cause

• The main control spool does not achieve full travel.

• The center position for the main control spool in the steering control valve is incorrect.

• There is oil leakage past the seals in the steering control valve.

• Oil leaked past the ball in the ball check valve that is located in the steering control valve.

• The seals on the steering cylinders leak.

Problem

The steering is jerky.

Probable Cause

• There is air in the steering system.

• The main control spool does not move freely in the bore of the steering control valve.

• The pressure setting for the relief valve in the steering control valve is set too low.

Problem

The machine turns slowly, even when the steering wheel is in the NEUTRAL position.

Probable Cause

• The center position for the main control spool in the steering control valve is incorrect.

Problem

The oil pressure in the steering system is low.

Probable Cause

• The pressure setting for the relief valve in the steering control valve is set too low.

• The hydraulic and steering vane pump is worn.

• The hydraulic and steering vane pump is leaking air into the system.

• A seal in the steering system has failed.

• The oil level in the hydraulic tank is low.

• The viscosity of the oil is wrong.

Problem

The steering pump makes noise but the cylinder rods do not move smoothly.

Probable Cause

• The hydraulic and steering vane pump is leaking air into the system.

• The hydraulic and steering vane pump is worn.

• The pressure setting for the relief valve in the steering control valve is set too low.

• The viscosity of the oil is wrong.

• The oil level in the hydraulic tank is low.

Problem

The temperature of the oil is too hot.

Probable Cause

• The viscosity of the oil is wrong.

• The pressure setting for the relief valve in the steering control valve is set too low.

• The hydraulic and steering vane pump is leaking air into the system.

• The hydraulic and steering vane pump is worn.

• There is a restriction in an oil passage.

• The load on the system is too high.

• The seals on the steering cylinders leak.