Getting hydraulic drive info is like pulling hens teeth...

[jerseybigfoot]

There is 2 directions to take, chain drive or wheel motors. The engine and pumps would be similar but the motor drive and performance level would change significantly.

[chris davison]

It would be nice to have a variable speed pump that put out 40 gpm at at 2000 psi max and then as load increased gpm would decrease. Lets say you are going on flat ground at 28 mph pumping 40 gpm at 1000psi. then as you start climbing that hill psi raises because of increased load but gpm decreases as does speed as torq increases. Now you are climbing that 35 degree hill hitting 2000 psi but only pumping 10 gpm. yes you have slowed down but torq has increased to climb the hill. This is possible with a sunstrand piston pump but the price is prohibitive and still uses 45 hp to do it. The only good thing is the piston pumps are the most efficient but the most suceptable to dirty oil.

[chris davison]

If you want speed and climbing ability It will cost$ Sunstrand piston pump 9-6557 $ 1100.00 50 gpm at 2000 rpm 2880 rpm max 3500 psi continus. (surplus center.com) It will also take a 100 hp diesel to power it and at least 100 gal oil tank with a cooler. It will be heavy but should do 40 mph and climb almost verticle. This is a variable diaplacement pump with the enging running at 2500 rpm you can change the gpm output from 0-55-60 gpm 5 gpm would be like a granny gear where 50 gpm would be like overdrive.

[stickalose]

Maybe I can contribute...I bought the Ratcliffe machine some were giggling about a while back. It's hydraulic. 6 wheel motors, 3 per side in series. Powered by a 60 hp Subaru engine coupled to a tandem variable displacement pump. Problem with matching engine max hp rpm (5000+) with hyd pump max rpm (3600), so inefficient match. It works ok tho. Definitely doesn't like cold startups (-20F). Replaced hyd oil with Dextron atf, helped a bit, but plan to refill with synthetic before next winter. Wish I could decouple the hydraulics till the engine is warmed up.
Motor rpms max are 250, with 26 inch tires, putts along ok. The parts are pretty old so i haven't been able to cross reference to any currently available stuff. I would suggest using tapered motor output ends, hubs are fairly cheap.

[chris davison]

That sounds like a lot of fun you have there. Those are some good ideas. Are you starting the Engine with the pump at 0 gpm output?
Maby you need a block heater like some diesels have. In the engine and the Hyd. tank. You can check with some oil companys like Chevron for thier coldest temp Hyd. oil. I think I would add a throttle stop at 3600 rpm just to be safe. Do you know the rpm for the max torq on the subie motor? Do you know the max gpm on the pump? I wonder if its possible to use a sliding splined coupling between the motor and pump to decouple it. also a 1.5 gear reduction to the pump would be great motor 5500rpm pump 3600
+ 50% more torq to the pump. Ive seen those tapered wheel motors on EBAY.

[stickalose]

Not too much fun, actually. I need the thing as part of my work commute. I park it at the pavement about a mile away, so it sits in the open for about 12 hrs. I've got an electric block heater and stick on pan heater for the hyd tank, but haven't installed them yet cause no power at road, so not 100% helpful. Looking at propane block heater, but there's not alot of head room near engine.
I'm kinda stuck with the existing layout. There's not alot of room to play with.

The charge pump is direct coupled. Once the engine is running it recircs back into the hyd tank, so the tank warms up, but the external lines, main pump, and motors are still cold until you drive a bit, 1/4 mile or so. Until then I just take it easy. I generally keep it about 2200 rpm after it warms up, to baby the tracks, they need work.
No info about the pump specs, obsolete, but it "looks" like Surplus Center item#9-7647, doesn't have aux gear pump.
Plan to install rev limiter this summer.
I dream about electic drive, like on mining equipment, but it's beyond my IQ and budget.

[chris davison]

The first thing I would do is use two batteries. At those temps this machine is to important to you not to start. The second is to put some tubing like 3/4 inch into your Hyd tank and run the radiator coolant through it. So you effectually have a heat exchanger warming your hyd oil as you warm the engine. Put a shut off valve on it also. Have you thought about a separate battery that you charge every night to run a 12vdc 50 watt heater through the day at work? It will be almost dead in 12 hrs but would help with the block temp.

[stickalose]

Interesting idea about heat exchanger. Thanks. I'll have to open dash to see if there's room.
I don't know about 12v heater, though. Running a battery flat at low temps ruins them after a while.
I do run synthetic oil in the engine.

[chris davison]

your right about the battery a 100ah battery will put out 100 amps for 1 hr or 1 amp for 100 hrs. 25 amps for 4 hrs or in your case 8 amps for 12.5 hrs so run 4 amps for 12.5 hrs and you will only run the batt down 50% 12vdc times 4 amps = 48 watt heater. running it down to 50% is ok for normal batteries but a deep cell rechargable can be run down to 20% left. Hope this helps.

Hey I forgot about solar battery chargers also.

[stickalose]

Yeah, I was planning to install a 500 watt heater anyway, could try feeding it 12 volts and it would be about 50 watts, nothing to loose. If it helps then could get creative with additional 12v power. Thanks.

[chris davison]

Hey I just had a thought why not use a spring wound timer to turn on your heaters one hour before you get to the machine then you could use bigger heaters because they will only run for one hour.

[stickalose]

That's an idea. I'll try the 500 watt on dc and see how it does. Been able to get in with a 4x4 this week. Maybe winter is over, I'll be able to work on it.

[chris davison]

If this heater is 500 watts it will draw41.66 amps of 12vdc remember the formula is amps x volts =watts so 500/ 12= 41.66 this rate would last 1 hr with a 100ah battery to draw down to 50% if this was hooked up to 117 vac it would draw 4.27 amps see the difference and the problem? Also most spring wound timers are only rated for 20 amps. Its not a problem if you use a relay rated for 50 amps and you only want to run it for 1 hr.

[Caveman]

Ok, while on this hydraulic thread, I have old Terra Tiger that I want to convert to hydraulic. Don't care much about more than 10mph speed. Have new 2 cylinder 18hp engine w/horz shaft to power a hydraulic pump. Will keep the chain setup to couple the tires and one hydraulic motor on each side to drive them. I am thinking of a 6-7 gal min pump but need to know what motors you guys would recommend or pump you would use as well. I had a skid steer (case 1845c) that had same type setup of course much beefier and with a diesel engine, maybe 80 hp or so. Since the Terra is not very heavy, things should be much smaller. This atv is for fun only and not to be seriously offroaded, just used around my property and lake to mess with. Thanks Caveman

[chris davison]

What is the top rpm of motor? what is the tire diameter? and what are your sprocket ratios? 16.3hp could give you 19 gpm at 1250 psi. At 2000 psi you get 12 gpm for 16.5 hp. this flow rate would be split to each side. Take into account not to many pumps go over 4000 rpm while most 2 strokes can go to 7000rpm. Most pumps are in the 2000 to 3000rpm and 2000 to 3500psi catagory.