How efficient is a hydraulic pump and hydraulic motor?

how efficient is hydraulic motor connceted to a hydraulic pump so the pump runs the motor. what kind of losses are there? is there a different lose at different speeds

If the components are new, the circuit will be relatively efficient. Inefficiency will be a function of leakage in the pump and motor.
The losses will go up with speed and load. The suppliers normally provide a graph that enables you to work out what the delivered power will be at a given load and speed setting.

Just a quick note about the above answer, liquids are compressible but at low pressures the compression is so low it can be virtually ignored. However in applications like fuel systems, operating at around 2000 bar, diesel is compressed to be 85% of its original volume.
hydraulics are terribly, terribly efficient because liquids are incompressible. Pneumatics suffer from inefficiency because air is a compressible fluid.

The only losses in hydraulics will be due to mechanical friction, viscosity of the liquid and flow friction in small tubing. Practically, there is also the problem of leaking hydraulic fluid.
Watch the first Terminator movie. the end scene where a hydraulic press kills The Terminator. So it is very efficient.
expect about 85% efficiency from the pump and 80% from the motor. It depends where you lie on the pump curve.

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