Hydraulic motor advice

[case685]

Hi All
I am looking at converting a 6ft snowblower to hydraulic drive. I want to start with the motor and I am seeing a Char-lynn #106-1228-006 motor on ebay that I think will work but I'm not sure. The specs are: 24.03 cu.in, 2250 psi, 6840 in lbs torque, 20 gpm and 191rpm.

The rpm I know is too slow so my plan is get where I need to be rpm wise with gearing rather than direct drive.

I have a Parker pump on hand that was used on a large industrial forklift to run the cylinders ( I cant seem to find specs for it online)-not sure if its up to the job but if not I will possibly look at a pto driven pump. Prince makes one that matches this motor pretty close on psi and gpm's.

Thanks in advance for any opinions and advice on this.
Gerald

 

[Dave M7040]

Start by telling us the tractor you have to power this arrangement.

There are significant losses as you convert mechanical torque to hydraulic and then back again so you need a big tractor.
My M7040 Kubota could not do this.

Your motor choice seems very wrong. 6840 in lbs which is 570 ft lbs of torque is far too much.
A theoretical before losses calculation says 570 ft lbs of torque needs 59 HP @ 540 rpm
Changing the speed of the motor involves additional power losses.

This pto driven hydraulic power pack illustration will give you an idea on power requirements.
52 pto HP!!!

Tell us more on why you what to do this.

Dave M7040

 

[CADplans]

Hi All
The rpm I know is too slow so my plan is get where I need to be rpm wise with gearing rather than direct drive.
Gerald

Well,, gearing will reduce the torque by the gear ratio,,
decreasing the hydraulic motor cubic inches will also reduce the torque by the displacement ratio.

It appears that using a 8 cubic inch motor instead of a 24 cubic inch motor will raise the speed by a factor of 3
and,, the 8 cubic inch motor will be 1/3 the torque.

I would think if you are trying to get close to PTO speed of 540 RPM,, choosing the right motor will get you there without gears,,,

 

[radios1]

I've seen a FEL mounted hydraulic snowblower, there was a post here about it, it does look like a great idea..

 

[case685]

Thanks for the replies...

My reason for wanting to do this is a result of age related issues with my neck back and hip that are making snow blowing with the 3pt a not too pleasant experience, by going hydraulic I was hoping to mount it on the FEL.

Based on Dave's comments I guess at 35 pto hp maybe my tractor just isn't up to the job. I have considered doing it mechanically using a gearbox and shaft running to the front of the tractor but I would need to make some type of front hitch to mount the blower on.

 

[case685]

I should also mention, in case going hydraulic is still viable with the right setup that my tractor has provision at the front to run a shaft from the engine pulley to the front of the tractor which is how I was hoping run the pump so the pump would be running at around 2600 rpm.

 

[oldnslo]

Case685
Would the front run whenever the engine is running or is there a clutch on this drive?

No matter where the pump is mounted you will still need a reservoir. These reasons are why the typical setup is on the rear PTO. Clutch to start and stop blower and reservoir / pump assembly are close to each other reducing length of inlet line. Added benefit is weight on the rear to offset blower weight on the front

For reference a good hydraulic drive will provide at best 75 - 80 % of input power as output power so 35 HP in = approximately 25 - 27 HP out. Lower quality components loss is even greater

Yes you can blow snow just slower

 

[radios1]

use a bent axis piston pump and motor.. 92% efficiency. Hydraulic Pumps and Motors: Considering Efficiency

 

[case685]

Oldnslo, my plan was to have the pump running whenever the tractor runs and actuate the blower with a valve, also planned to mount a reservoir on the blower itself. I figured on keeping my blade on the 3pt for ballast.

I had the 5hp per foot rule in my head when thinking about whether my tractor could handle the load but it's looking like that rule doesn't apply when going hydraulic. If I accept the idea of blowing slower can I still have a setup that runs the blower fast enough to throw the snow a good distance?

Radios1, I will take a look at those pumps but I am starting to think a mechanical setup might be a better option for me. I actually looked for an electric pto that I could mount on the front of my tractor and run it off the main engine pulley the same way I was planning to run the pump but they don't seem to make one big enough for a setup like I'm contemplating.

 

[radios1]

there's a whole bunch of electric clutches listed here. designed for this, and definitely big enough. electric clutch hydraulic pump - Google Search