Why Choose a Hydraulic Motor over an Electric Motor?

[Ronnin]

I'm a store manager for an industial distributor here in Houston. I have several lines for electric motors but don't get into any hydraulics. I had a customer ask me to quote him on a Vickers hydraulic motor and it made me curious as to why someone would choose to go with a hydraulic motor vs an electric. Are there any cut and dry reasons why one would spec one versus the other? Just curious.

 

[mgb_phys]

You get a lot of power and torque in a small package.
Also handy if you have compressed air/hydraulic power available anyway - like in an excavator or you want to avoid any sparks or electric shock risk with water - like in tunnelling

 

[Topher925]

You get a lot of power and torque in a small package.

Indeed. A hydraulic motor about the size of your fist can easily put out around 7kw of power. You can commonly find hydraulic motors on cooling fans of equipment that already have hydraulic systems. For example a front end loader or excavator. Also, the Jeep Commander and Jeep Grand Cherokee 05-09 (I think) models have hydraulic motors powering their cooling fans.

 

[Ronnin]

Good info. I appreciate the responses. I can't stand when I'm asked about product I don't know enough about.

 

[Danger]

I don't know whether this is universal or not, but I've found hydraulic motors to be much quieter than electric ones. That is assuming, of course, that the pump is in a remote location.

 

[Enthalpy]

I built tracks for crashtest before. Both hydraulic and electric motors were possible to pull the car (...or the truck) to be crashed.

Hydraulic motors are indeed smaller at identical power and especially torque. Their speed and position can be regulated very well, though not as precisely as for electric motors. Price also was a bit lower because of the inverter.

A very distinct advantage for us was the ability to store energy in 300b nitrogen and release 1MW power or more to the hydraulic engine. Electric motors were only possible where the mains allowed such powers. Batteries can't compete.

As for actuators - that is, cylinder as compared to electric motor+spindle, the advantage was even clearer. The spindle could give a high force and even power in an acceptable volume, but by no way could it react as quickly as a valve +hydraulic cylinder does. We regulated 3MN (the weight of 2 locomotives) within 10ms with a few % precision: don't even dream of it with electric motors, alas.

The dark side of hydraulics is the fluid, so this is quite hopeless. It does leak often. It does require maintenance. It does fail. And it's dirty.

 

[Widder]

Hello Everyone, please bare with me, I'm new at this. Ron, the question of Hydraulic vs. electrical in the motor realm is a no brainer if you could compare the two. As stated by the posts, hydraulic motors the way to go once the prime mover has been decided on. Your customer was probably buying that motor to be attached to an electric motor to move fluid for whatever reason or attached to an internal combustion engine to activate accessories i.e. power steering, front end loader bucket or engine starting unit. That Hydraulic will need a prime mover to actuate.