Proposed is a dosing module for injecting liquid urea-water solution into the exhaust tract of an internal combustion engine, which dosing module is composed of two pumps, specifically a delivery pump (5) and an aeration pump (15). This permits firstly the injection of urea-water solutions and secondly safe and reliable ventilation of the system when the internal combustion engine is to be shut down.

A balanced piston pump (300) for use in subsea vehicles, for example in a variably buoyancy engine, includes an inlet (321), an outlet (325) and at least one fluid path between the inlet and the outlet. A piston arrangement in the fluid path includes a stepped piston (330) having a large end (333) and a small end (331). The step (336) of the piston cooperates with the body (310) of the pump to form a piston chamber (320). The ends (332, 334) of the piston are each exposed to ambient pressure. The force required to drive the pump is dependent on the difference in cross sectional areas of the ends of the pistons.

A drive system for an industrial handling vehicle comprises an electric motor, a first pump, for example, a plunger pump, and a second pump, for example, a gear pump. The first pump is configured to provide hydraulic power for a travelling device of the industrial handling vehicle. The first pump and the travelling device are in a first hydraulic circuit. The second pump is configured to provide hydraulic power for a brake device and/or a steering device and/or a handling device of the industrial handling vehicle. The second pump, the brake device, the steering device, and the handling device are in a second hydraulic circuit isolated from the first hydraulic circuit. The electric motor is operatively coupled to both the first pump and the second pump, to drive them to operate.

A drive system for an industrial handling vehicle comprises an electric motor, a first pump, for example, a plunger pump, and a second pump, for example, a gear pump. The first pump is configured to provide hydraulic power for a travelling device of the industrial handling vehicle. The first pump and the travelling device are in a first hydraulic circuit. The second pump is configured to provide hydraulic power for a brake device and/or a steering device and/or a handling device of the industrial handling vehicle. The second pump, the brake device, the steering device, and the handling device are in a second hydraulic circuit isolated from the first hydraulic circuit. The electric motor is operatively coupled to both the first pump and the second pump, to drive them to operate.