Hydraulic motor education needed..

[davedj1]

for turning a mast. I am building a crane of sorts for the front of my dump trailer and would like to have power swing. My thought is a ring gear and pinion with the pinion being driven by a low rpm high torque hydraulic motor.
Here is the smallest volume one I found at SC
.5 cu in Char-Lynn 129-1 Hydraulic Motor | Low Speed High Torque Hydraulic Motors | Hydraulic Motors | Hydraulics | www.surpluscenter.com
given the gear reduction of lets say 4-1 with the ring and pinion, the motor above specs state : 1992 RPM cont.
2458 RPM int.
would that then drop the rpm to around 500? and if so, would limiting the flow via the control valve with an orifice or just not moving the control valve far give me a slow enough speed?
My other option is chains and a double ended hydraulic cylinder but the ring and pinion seems to be more compact, and I have access to them.
Edit: I just found this one at NT, https://www.northerntool.com/shop/t...90Cw458-lEblaY-k4Sy0TgxfGB0wt6UAaAizoEALw_wcB it may work better?
Thanks in advance
Dave

In case it matters I will be running the whole crane with a 6.5 hp Predator gas motor and a 5-7 gal/min gear pump. It will have up/down, in out and swivel with a winch on top of it. I would like to build a hydraulic winch but that's another can of worms...LOL

I also was thinking maybe an electric rack and pinion out of a car but not sure it would have enough travel.

 

[MossRoad]

Small displacement hydraulic motor is high speed with low torque, like my hydraulic mower deck. I'd think you'd want a high displacement motor with low speed and high torque for that application, like on a hydraulic tiller or winch or post hole auger head.

 

[SPYDERLK]

You are going to need a lot more torque than 12 ft-lb I think. Are you needing a 360 swing? Or just 180 or less? You might be better off by using hyd cyls if a limited swing is suitable.

 

[davedj1]

You are going to need a lot more torque than 12 ft-lb I think. Are you needing a 360 swing? Or just 180 or less? You might be better off by using hyd cyls if a limited swing is suitable.

I would like 360* rotation in case I want to put something in or out of the truck.

 

[oldnslo]

davedj1,
When deciding on motor size you need to determine what torque is required and then start figuring size from there. Torque is a function of motor displacement & pressure across the motor.

Speed is a result of system flow divided by motor displacement. In USA simplistic formula is GPM times 231 divided by motor displacement in cubic inch per revolution.