Very Low Speed Hydraulic Motor

[wistudenteng]

Hello,
I am building a hydraulically operated weld positioner for my internship. The weld positioner has a rotating plate with required output of 750 lb-ft. at .02-1.3 rpm. What do I have to do to achieve that high torque at such a low rpm? Do you recommend gearing, or can I control it with a flow controller. Do I have to worry about minimum speeds on the motor? Any advice would be appreciated.

 

[FACS]

Well, I would recommend gearing, you do have to worry about min. motor speed, depending on the motor.

We use planetary or harmonic gearing.

Charlie

http://www.facsco.com

 

[HvyLiftr]

You will probably benefit by chosing a closed loop hydrostatic transmission with a fixd displacement motor and variable displacement pump to drive your system. The pump can be electrically controlled to vary the speed and direction of the machine.

Use the gearing that Charlie suggested, you can keep the drive components at their optimum efficiency points for speed and pressure. In general, choose the largest numerical gear ratio and the largest motor displacement that will give you the torque you need at the optimum transmission motor speed and pressure. The gearing also minimizes effect of speed ripple.

 

[jcarrr]

Some hydraulic motors are available with harmonic gearing

The cheapest drive will probably be a tiny pump/motor device coupled to a 90 volt DC motor driven by a minimal DC ASD.

Will you be graded for introducing pressurized, combustible fuel to a welding location? Might investigate alternative fluids.

 

[unclesyd]

Take a look at these motors. I've run them at very low rpm for days on end. In my application they would tend to stall due to load.

I would give the following company or Eaton a call as there are so many options and configurations available.

http://www.charlynn.com/

 

[wistudenteng]

Thanks for all the input. I hadn't considered the threat of the heat from the welding operation, so I will have to do some experimenting to determine how much heat the unit will be exposed to. Good advice.

 

[dvd]

Don't forget about grounding your workpiece. If you have welding current passing through the bearings on the hydraulic motor someone will end up disappointed.

 

[ornerynorsk]

Piston motors can generally be used at very low rpm with tremendous torque. I'm thinking of a power feed unit I saw on a large Cincinatti simplex horizontal mill.