The second , most important part of the muscle module is the bidirectional , miniature gear pump . After a lengthy search I found a pump which is almost perfect for this project - a miniature gear pump made by MAGOM HRC company , and intended to be used in RC construction machinery models.

The pump needs to be modified a bit :
   - first remove all the hoses from the pump and unscrew the hose connectors
   - remove the oil tank
   - dismantle the pump
   - remove the screw holding the pressure regulator , and dismantle it
   - drill the pressure regulator hole with 4mm drill , and tap it with M5 tap
   - thread the inlet hole in the pump cover with the M5 tap.
   - plug the hose connector holes and oil tank mounting hole with headless screws
   - install the 4mm push-in connector in the newly threaded M5 holes
   - reassemble the pump

The modified pump should look like this :

The last step is to install the BLDC motor. If the motor does not fit the pump it may be required to build an adapter and modify the original mount ( as it was it my case  ) .