Dynamic Response Pump

The Dynamic Response hydraulic pump is located on the RH side of the engine. The pump is attached to a mounting bracket below the generator on TDV6 engines and above the generator on V8 petrol engines. On both engines the pump is driven by the accessory drive belt from the crankshaft.

ITEM	DESCRIPTION
1	Cam ring
2	Cylinder housing
3	Inlet port
4	Outlet port
5	Shaft
6	Silencer volume
7	Discharge valve
8	Piston spring
9	Piston
10	Housing
11	Counter balance
12	Pulley attachment flange

The hydraulic pump is driven at approximately 1.7 times crankshaft speed by the auxiliary drive belt. The pump is a radial piston type which delivers fluid at high pressures.

The radial pump has eight pistons located in bores in a cylinder housing. A balanced central shaft, which is driven by a pulley and the auxiliary drive belt, has a cam which operates the pistons as the shaft rotates.

As the cam lobe reaches each piston, the piston is pushed outward, moving the fluid above the piston. The pressure created by the fluid flow from the bore opens a spring loaded discharge valve. When the valve opens, the now pressurized fluid flows, via the silencer volume area of the cylinder housing, to the outlet port. The silencer volume assists with damping out operating noise from the pump. When the piston reaches its full stroke, the flow reduces and the discharge valve closes under spring pressure.

As the cam lobe moves away from the piston, a spring pushes the piston down the bore, creating a vacuum above the piston. As the piston moves down the bore, ports in the piston are exposed and connect with the fluid inlet port. The vacuum draws fluid into the piston filling the piston and the chamber above it. As the piston is again pushed upwards, the ports in the piston are closed off by the bore and the pressurized fluid opens the discharge valve and flows to the outlet port.

The above sequence is applied to each of the eight pistons for every revolution of the shaft and cam. When the engine is running the sequence occurs rapidly creating a constant flow of fluid. The fluid flow varies with engine speed and the rotational speed of the shaft. The pressure applied to the actuators, created by the flow from the pump, is controlled by the pressure control valve in the valve block.

The pump has a displacement of 6cm³ /rev and an operational pressure of 165 bar (2248 lbf/in² ). The pump output flow ranges from 6.5 l/min (1.7 US Gallons/min) at idle to 10 l/min (2.64 US Gallons/min) at 1000 rev/min and above.