PIPE AS-EXHAUST 1786487 - Caterpillar

Primary Steering System Operation
The steering system is hydraulic. There is no mechanical connection between the steering wheel and steering cylinders (1) that move the front wheels. The steering system is a closed center system. The steering system is independent of all other hydraulic systems. Oil for the steering system is stored in steering hydraulic tank (16).Steering piston pump (18) is a pressure compensated piston type pump. The steering piston pump is mounted to the left rear face of the flywheel housing. Steering piston pump (18) is driven by the flywheel. Steering piston pump (18) operates only when the engine is running. The output of the steering piston pump is controlled by pressure and flow compensator valve (19). Metering pump (20) receives signal oil from the pressure and flow compensator valve. The signal oil flows through shuttle valve (9) and to the steering metering pump. The signal oil determines the pressure and the flow of the steering piston pump. The pressure and flow compensator valve is fastened to the steering piston pump. The flow compensator valve in the pressure and flow compensator valve causes the steering piston pump to change from low pressure standby to full flow. The high-pressure cutoff valve limits the maximum steering pressure.Internal leakage from steering piston pump (18) is returned to steering hydraulic tank (16) through steering pump case drain filter (17). Return oil from the steering system flows through steering oil filter (15). The steering oil filter is bolted to the steering hydraulic tank. Normally, oil flow through steering oil filter (15) and clean oil is returned to steering hydraulic tank (16).If the filter element for steering oil filter (15) becomes full of debris, the restriction to flow causes a pressure increase. The bypass valve for steering oil filter (15) will open when the pressure increases above the setting of the bypass valve. When the bypass valve opens, oil is allowed to bypass the filter. The oil goes directly to steering hydraulic tank (16). When the oil bypasses the filter element, debris in the oil will damage other system components. Proper maintenance must be used to ensure that the filter element does not stop the flow of clean oil to the hydraulic system.Steering hydraulic tank (16) supplies oil to steering piston pump (18). The steering piston pump (18) pumps oil to primary steering relief valve (6). Primary steering relief valve (6) is mounted in steering check and relief valve (2). The primary steering check valve prevents oil from flowing back through steering piston pump (18) if the engine stops. From primary steering relief valve (6), the pressure oil flows to the steering metering pump (20). When the steering wheel is turned, steering metering pump (20) sends a fixed amount of oil to steering cylinders (1). The speed of the turn is determined by the rate of the steering wheel rotation. The steering linkage is designed to use the head end of each cylinder as a mechanical stop.Two steering cylinder check and relief valves are