Investment casting in drive technology

Pump impeller

Pump wheel - Lorry hydraulic retarder

The hydraulic retarder is installed in commercial vehicles. Its advantages lie in the reduction of weight, the replacement of oil as an operating medium and the achievement of a higher continuous braking performance as well as freedom from wear and maintenance to the greatest possible extent. By relieving the load on the brake system, the brakes are protected. The lower wear also enables a reduction in brake emissions. The retarder is connected to the gearbox via a gear up setting. Thus, the braking process takes place directly on the drive train. The hydraulic retarder is activated via the braking system. The control pressure on the valve block opens filling chambers and the water from the cooling circuit flows into the working circuit. The rotating rotor takes the cooling water with it. This shifts the rotor from idling to braking and decelerates the PTO shaft, causing the vehicle to brake.

The challenge with this component lies in the geometry and dimensional requirements. The aim is to achieve the lowest possible unit weight in relation to the required functional diameter. Due to the high demand on dimensional accuracy, very tight manufacturing tolerances must be observed. In addition, the blades of the wheel should be as thin-walled as possible in order to achieve the highest possible efficiency. Due to the high requirements, the investment casting process offers considerable advantages compared to full machining - not least in terms of the cost factor.