Hydraulic pump and motor questions

Pooh_Bear · Aug 16, 2009

I have a vertical shaft engine.
Can a hydraulic pump be mounted vertically to this engine.
Should it be direct driven or can it be belt driven.

I have a 46 inch mower deck.
What size hydraulic motor would it take to run it.

And finally, I want to mount this all on a frame
and use a hydraulic motor to propel it.
What should the specs be on this motor.

If you haven't guessed already I'm thinking of building
a riding lawn mower with everything powered hydraulically.

My big question for now is, can a hydraulic pump be mounted vertically.

Thanks.

Pooh Bear

bobodu · Aug 16, 2009

I mount them upright all the time. Pump don't care as long as it's filled with oil.
I also like to run them off a belt. It gives some measure of protection like a shear pin and allows me to change a pulley it I want more flow or pressure.
Now before someone points out the pressure thing...I mean I have had pumps that would slip the belt before getting the pressure up to where I wanted it. A larger pulley on the pump solved this.

Take a look at your deck and see what kind of reduction the present pulleys provide as to speed needed for the deck. Most small engines run in the 3200 to 3600 rpm range. Be prepared to spend a lot on oil and carry it all around as well as some way to cool it. This is another can of worms but figure on 15 gallons or more.

tanglefoot · Aug 17, 2009

Bob,
I'm wondering why you would need so much hydraulic fluid on one of these small machines. The reservoir on my Ford 4500 fel has only a 5 gallon capacity with its 23 gpm pump. It works quite well.
Butch

Opti-Mist · Aug 18, 2009

Consider the load cycle. On the 4500 it is intermittant where on the mower it will be continuous. Load = heat.

bobodu · Aug 19, 2009

Yep...heat. Add another motor to move the thing and you'll be up to frying temp in no time.
Although I have never stopped to look at one,I imagine the golf course mowers have some pretty big oil coolers. The highway bank mowers have a big tank on the left side of the cab and that also acts as a counter-weight.

Oh...forgot all about this....another reason to run the pump off a belt on a mower is that if you hit something with the deck and that motor turns into a pump....you won't bust a crank on the engine. Ideally, you might wanna consider a shear pin or something like it on the deck.

westcliffe01 · Aug 19, 2009

Get a gear pump for powering the hydraulic motor on the mower. Take a careful look at the maximum rpm for both the pump and motor. The mower spindles typically turn pretty fast. Many pumps are rated to turn at 3600rpm. You will need a high rpm hydraulic motor like these listed here:https://www.surpluscenter.com/sort.asp?UID=2009081921305432&catname=hydraulic&keyword=HMHS

And the previous poster was right that you would need a substantial oil cooler with an electric fan to move air through it since ground speed is typically low.

Pooh_Bear · Aug 20, 2009

Wow, a lot to think about. Didn't consider the heat issue.
Glad to know I can run it using belts and pulleys. Simplifies things.
It will still end up being bigger than a regular lawn tractor.
Mite as well add some extra capabilities while I'm at it.

Still haven't figured out how to get the variable speed to drive it.
All I can think of is one of those variable flow controllers.
Need to be able to just creep along, or as much as 10mph.

Pooh Bear

mjncad · Aug 20, 2009

Be sure to post pictures, this sounds fascinating.

bobodu · Aug 20, 2009

You're also gonna need either a rotary flow divider,a double pump or two pumps of you want to run the drive hydraulically.

RPW · Aug 21, 2009

You might want to get some specifics from the people on the hydraulic board. Wayne comes to mind at the moment. I found (but don't remember where) that you typically want 1 gallon of resivoir for each gpm of pump. This also serves to allow micro bubbles to work there way out of the oil (prevents foaming). I've found that working with hydraulics is pretty straight forward and interesting but v-e-r-y messy.