Description   Hydraulic motors are powered by pressurized hydraulic fluid and transfer rotational kinetic energy to mechanical devices. Hydraulic motors, when powered by a mechanical source, can rotate in reverse direction and act as a pump.  Operating specifications and features are the most important parameters to consider when searching for hydraulic motors.   Types The most important attribute to consider when searching for hydraulic motors is the motor type. ...
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Q & A on Hydraulic Motors

We asked our users for their input on Hydraulic Motors. Here are the results of 301 users familiar with Hydraulic Motors.

Who Took Our Poll? | Design Trends | Applications and Use | Features | Buying Advice

Who Took Our Poll?Top

Design TrendsTop

Q:
What new technologies are influencing hydraulic motor design?
41 answers
Answers:
Piston motors: electronics, 0 degree capability, good efficiency at low speed orbit motors: integrated valves, integrated brakes, high pressure shaft seals, integrated sensors
~Maurizio A, Marketing/Sales, Parma, Italy
Things like horse power limiter, torque limiter, new design in machine with load sensing and electronic control influence the choice of hydraulic motors.
~Claude L, General Management, Montreal, Canada

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

~Colin G, Design Engineer, Shanghai, P.R.China
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Q:
From your perspective, which companies are creating the most innovative hydraulic motors?
48 answers
Answers:
Sauer-Danfoss is a very good manufacturer of hydraulic motors and also quite impressive in creating, designing and marketing a new product from scratch to the production level and to the O.E.M. customer.
~Claude L, General Management, Montreal, Canada
1)Hagglunds drive (radial piston motor) 2)Linde hydraulics (axial piston motor) 3)Sauer-Danfoss (orbital motor)
~Colin G, Design Engineer, Shanghai, P.R.China

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

~Maurizio A, Marketing/Sales, Parma, Italy
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Applications and UseTop

Q:
What are some of the applications you have used a hydraulic motor for?
87 answers
Answers:

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.

~Jim A, Owner, Alternative Energies, Inc., Indianapolis, IN

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.

~Warren K, Manufacturer, Toronto, Canada

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...............................

~Robert J, Valuable, Untitleable, Houston, TX
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Q:
Please share with us any “non-standard” applications that a hydraulic motor has been used for.
29 answers
Answers:

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.

~Mike L, Manufacturer, Mississauga, Can

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.

~John M, Technical Support, Vancouver, WA

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

~Colin G, Design Engineer, Shanghai, P.R.China
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Q:
Do you know of any disastrous mistakes that occurred due to the incorrect usage of a hydraulic motor?
16 answers
Answers:

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.

~Mike L, Manufacturer, Mississauga, Can

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.

~Norm E, Automotive Technical Trainer, Mount Evelyn, Australia
Using a gerotor style motor that is high torque, low speed due to compact size and the motor not being able to handle system loads in a hydrostatic drive where operator abuse is possible without adequately compensating with full flow counter balance valves.
~John M, Technical Support, Vancouver, WA
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FeaturesTop

Q:
What would your design or feature "wish list" be for this product?
36 answers
Answers:
Able to handle higher case pressure spikes in high pressure seal area. Full flow counter balance capability on power reversal.
~John M, Technical Support, Vancouver, WA

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

~Phaniraj K, General Management, Secunderabad, India

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

~Toddy R, General Management, Point Lisas, Trinidad W>I>
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Q:
Is there any advice you want to share with users to help them avoid common errors in selection or usage of a hydraulic motor?
18 answers
Answers:

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.

~Mike L, Manufacturer, Mississauga, Can
Correct application with matching load - torque characteristics, use of correct lubricant and contamination free design of pipes and other accessories.
~Phaniraj K, General Management, Secunderabad, India

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

~Cyril L, Manufacturer, Sligo, Ireland
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Buying AdviceTop

Q:
Do you have any advice for people relative to buying or using a hydraulic motor?
26 answers
Answers:

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.

~Colin G, Design Engineer, Shanghai, P.R.China

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.

~Mike L, Manufacturer, Mississauga, Can

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.

~Robert J, Valuable, Untitleable, Houston, TX
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