Power steering pump Kamaz

The power steering pump with oil reservoir is installed in the camber of the cylinder block and is driven by the engine crankshaft.

The pump is a vane type, double-acting, i.e. for one revolution of the shaft, two complete suction cycles and two discharge cycles are performed.

Kamaz power steering pump

The position of the stator 37 relative to the housing 40 and the distribution disk 34 is fixed with pins.

An arrow on the outer surface of the stator indicates the direction of rotation of the pump shaft.

When the pump shaft 5 rotates, the plates are pressed against the curved surface of the stator under the action of centrifugal force and oil pressure entering the space below them from the cavity

In the cover of the pump 29 channels in the distribution disc.

Variable volume chambers are formed between the plates and the end surfaces of the pump casing and the distribution disc.

Kamaz power steering pump

At each moment, two of them form a suction zone: the space between the plates is filled with oil, and the other two are injection zones: the volume between the plates decreases, and the oil is displaced through the channels in the distribution disk into the cavity of the pump cover, which communicates through a calibrated hole A with discharge line.

In the pump cover there is a combined valve 33, which combines the safety and bypass valves.

The safety valve is adjusted to a pressure of 85 ... 90 MPa, and the bypass valve controls the amount of oil entering the system.

At the minimum crankshaft speed, the bypass valve is pressed by spring 30 against the distribution disk.

Oil from the cavity in the pump cover through the calibrated hole A enters the channel connected to the discharge line.

The cavity under the valve, where the spring 30 is located, communicates with this channel with a hole B of small diameter.

With an increase in the crankshaft speed, and hence the oil supply to the pumps, a pressure difference is formed (due to the hydraulic resistance of hole A) in the cover cavity (in front of the valve) and in the pump discharge channel (behind the valve).

The pressure drop is greater, the more oil passes per unit time through hole A, and does not depend on the pressure value.

Excessive pressure in cavity B, acting on the left end of the bypass valve, overcomes the resistance of spring 30.

At a certain pressure difference, the force tending to move the valve increases so much that the spring is compressed and the valve, moving to the right, opens the exit of part of the oil from the working cavity B of the cover to the tank.

The more oil the pump supplies, the more it is bypassed through the valve back into the reservoir. Thus, as much oil enters the system as required.

At low oil flows and an increase in pressure in the spring cavity, the built-in safety valve is activated, while the bypass valve will work in the same way.

When opening, the safety valve allows a small flow of oil into the reservoir through the radial holes D.

In this case, the pressure due to the resistance of channel B on the right end of the bypass valve decreases.

Valve 33 moves to the right and opens the outlet to the tank for the main part of the bypassed oil.

The safety valve should be adjusted using shims 32.

To prevent noise and slow down wear of parts when the pump is operating at a high speed and intensive oil bypass, a manifold 24 is provided, which directs this oil into the internal cavity of the pump housing and at the same time provides excess pressure in the suction zones.

In the tank 22 of the pump there is a collapsible strainer 23, which is a package of individual filter elements, which, in case of significant clogging, is pressed upward by the increased pressure in the cavity of the filter tube.

In this case, the oil flows directly into the tank.

In addition, the tank has a filling filter 14 and a safety valve 19 that prevents the air pressure in the tank from exceeding 30 kPa.