Hydraulic Motors - Insights

1) Distributor valve or port plate 2) Hydrostatic balance piston with orifice jet 3) High pressure shaft seal

Piston motors: Sauer-Danfoss. Orbit motors: Sauer-Danfoss, Eaton, Parker

I have tinkered with designing a four wheel drive vehicle that reverses the hydraulic to compress air in order to harness kinetic energy from a moving vehicle to use in restarting after stopping. This would eliminate thousands of tons of brake dust in our environment. It would also go a long way in reducing fuel usage and almost double fuel economy in our vehicles. Kinetic energy is all wasted in brake friction on our vehicles as they are presently engineered. I also have a new design for a windmill that uses hydraulics in the power train.

Hydraulic driven generators from diesel engine, hydraulic variable speed winches, hydraulic driven conveyor drive, hydraulic driven transmission to wheels, hydraulic marine propulsion, hydraulic digging chain in earth trenching machines, hydraulic boring augers.

Vehicle drives, crawfish boat, shrimp boat, ship applications, concrete vibrator, saws - big and small, cranes drive and winch, excavators, bobcats, etc., track drives, CNC machinery...............................

Ahh the horse trainer-- the horse was installed in a bathtub then the tub was flooded with temperature controlled water and the floor ( a belt) was activated via a hydraulic motor and a variable speed drive to force the horse to trot. The water added buoyancy to the horse to relieve stress on the legs at the same time the water added resistance to the fore and aft movement of the legs.

Propelling a truck chassis through a manual transmission high low range box for a hydraulic excavator application. Use in conjunction with an automatic transmission for under carriage propel. Variable speed control of a high pressure water pump on a sewer jetter application.

1) Tension control for conveyor belt 2) Vibration source for geological research

An SAI unit rated for the torque and pressure failed within 1 hour of testing.  The manufacturer then stated the maximum ratings as stated in their catalogues was only for 2 minutes out of each hour.  We were not at the max.  A replacement Dowmax unit, even though rated at less torque, was installed and operated at less than expected pressures.

I just recently replaced a drive motor on a Caterpillar 777 off highway truck that had failed because of oil contamination. This was super expensive for the owner. I believe it was the result of the operator not being instructed in the correct processes for vehicle maintenance.

Lightweight, highly reliable, maintenance friendly, easy availability of spares at cheaper prices and service back up.

Cooler working temperature, thereby extending the life of pumps in tropical climates.  And no sweating on coupling.

Mainly the torque/speed ratings are theoretical numbers. Decreasing to about 85% for maximum will just get you to the starting gate. For maximum life, oversizing to a substantial amount at much lower than rated pressure is recommended.

Make sure the control valves can allow enough oil to feed the motor.

1) After doing the selection of torque/ pressure / displacement of the motor, please retrospectively check whether the working speed is in normal. 2) When the working speed reaches above 80% of rated speed, a motor case flashing circuit should be considered in most applications. 3) The static internal leakage should be considered as the most important safety issue in hoisting applications, thus, the adequate and continuous back pressure should be built in main return line.

Most people have no idea what and how to use a hydraulic motor. Does any other motor supply full torque at stall with no adverse affects?  Can you instantly stop and/or reverse direction at full torque? Does size matter?  If so, the size to weight ratio can not be beat. Note: that if you increase the torque by going to a larger motor you will decrease the speed.

Hydraulic theory applied with a knowledge of component operation is a lost art in the distribution industry, replaced now by a mentality of part numbers only with no idea of what they represent. Get educated.