Coupling for powered trailers

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Originally Posted by roverrescue

But Ben, when Im on a pushie, if I have the chain on the little cog at the pedals (think pinion) and big cog at the back (think crown) its bloody hard to push the pedals... dosnt a 4.7 diff mean the crown has 4.7times the teeth of the pinion?

I had thought hydraulic... I did like the thought of hydro wheel motors too BUT also needs too quickly and easily free wheel. Half shafts and free wheeling hubs are cheap and easy to come by.

Any ideas on a source for hydraulic motors? Especially wheel motors? Are ag implemet motors going to be a starting point?

There are lots of powering possibilities. Just pondering the best/easiest/ghettofab capable path of least resistance.

Part of me thinks I should start building the trailer and then incorporate drive at a later date BUT if there is some vital component like a driveshaft that needs to be incorporated it makes sense to plan for that.

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Little cog (chainring) on the front and big cog on the groupset at the back is a LOT easier to turn than vice versa. You have to pedal a lot faster, but the effort required to commence movement is a lot less.

Just like it is much easier for the engine to move a car in first than 5th.

4.7: 1, you are right, a series diff has 10 pinion teeth and 47 CW teeth. So 4.7 turns of the pinion for one turn of the axle.

Bush65 is the best person to ask about hydraulic motors. However any ag stuff is a good place to start. No reason you can't have a wheel motor and a FWH grafted together.

no a higher ratio means more turns of the input shaft for less turns of the axle which means that you get more torque but less speed, which to me sounds ideal for getting the trailer to push along at low speed.

if you put the chain on the largest chain wheel and the smallest cluster gear (at the wheel) on a push bike then stand up on the pedal you will cover more distance but you will do so slowly at first and then get faster.

if you put it on the smallest chainwheel and the largest cluster gear you'll go a very short distance but you'll take of quicker.

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Originally Posted by roverrescue

But Ben, when Im on a pushie, if I have the chain on the little cog at the pedals (think pinion) and big cog at the back (think crown) its bloody hard to push the pedals... dosnt a 4.7 diff mean the crown has 4.7times the teeth of the pinion?

I had thought hydraulic... I did like the thought of hydro wheel motors too BUT also needs too quickly and easily free wheel. Half shafts and free wheeling hubs are cheap and easy to come by.

Any ideas on a source for hydraulic motors? Especially wheel motors? Are ag implemet motors going to be a starting point?

There are lots of powering possibilities. Just pondering the best/easiest/ghettofab capable path of least resistance.

Part of me thinks I should start building the trailer and then incorporate drive at a later date BUT if there is some vital component like a driveshaft that needs to be incorporated it makes sense to plan for that.

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If it's just for a boat trailer, therefore long front and rear overhangs, then mechanical drive is probably easiest and cheapest.You'll never exceed the driveshaft angularity limitations with a boat on, so the hitch and driveshaft probably won't need to be concentric.If your vehicle is fitted with an LT95 transmission, the high/low range PTO is the go, but if it has an Lt230 or Series T/case, then an additional transfercase on the trailer drawbar is the solution.Series or coiler axles can be widened an extra 9'' or so by lengthening the short side axle tube to centre the diff and run a long halfshaft each side.
Bill.

I would think that the hydroulic route would be the way to go, with a hydraulic motor either on the diff (simplest) or on each wheel. Agricultural equipment suppliers would be the way to go. Best would be a pump driven off a PTO, but an engine driven pump would work. Not sure about the steering pump though - you really need a much bigger reservoir or things would get awfully hot awfully quickly. Some decisions would need to be worked out on size of pump (pressure and volume) and motor requirements/gearing - fairly simple calculations, but you need to decide on what speed you need the assist - a variable displacement pump would help flexibility. Agricultural quick connect fittings would be the way to connect.

John

Brainfart - all makes good sense now....

Well then. If hydraulic: what flow and pressure is the PS pump good for... as opposed to an MR Automotive PTO hydraulic pump. I sent them a query but havent heard back with ratings of the PTO hydraulic pump.

dave, would not there be a risk of stalling/burning and electric motor if trailer traction/mass cannot be overcome by available torque? Is there a way I can calculate size/output of motor required with some rough inputs?

I do like the concept of electric, I already have the fender wired up to operate a Warn9000 on the big boat trailer. If i was to run a trailer diff driven by a driveshaft up to the winch post the electric motor would be relatively clear of mud and water. If needed I have a few old winches lying around which could have planeteries butchered to alter the driven shaft speed???

S

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Originally Posted by JDNSW

I would think that the hydroulic route would be the way to go, with a hydraulic motor either on the diff (simplest) or on each wheel. Agricultural equipment suppliers would be the way to go. Best would be a pump driven off a PTO, but an engine driven pump would work. Not sure about the steering pump though - you really need a much bigger reservoir or things would get awfully hot awfully quickly. Some decisions would need to be worked out on size of pump (pressure and volume) and motor requirements/gearing - fairly simple calculations, but you need to decide on what speed you need the assist - a variable displacement pump would help flexibility. Agricultural quick connect fittings would be the way to connect.

John

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for those with an ISUZU, 6BD1 PAS pumps are reported to be larger than 4BD1.

Would a viscous coupling in a mechanical set up be beneficial so there isn't any wind up? Would it also prevent the trailer from overpowering the vehicle in those rolly polly situations, if it couldn't lock up?
I know nuffink about autos and VCs so laugh at me if i'm way off the mark :)

Edit: I could be thinking of fluid couplings or torque converters or something...

The idea I have been toying with is to use Bobcat hydraulic motor on each wheel & a freewheeling hub each. plenty of grunt & very simple to engineer.
Hydraulic pump on pto - no brainer.

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Originally Posted by isuzurover

for those with an ISUZU, 6BD1 PAS pumps are reported to be larger than 4BD1.

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I have not done any calculations, but I doubt the size of the pump is the problem (particularly for the Isuzu) but the reservoir size is. There are significant losses in this sort of hydraulic system, and that all ends up as heat in the hydraulic fluid. Most such systems use the reservoir for cooling, although a heat exchanger may reduce the size of reservoir needed. Not a problem with steering, as it is essentially an intermittent use.

John

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Originally Posted by goingbush

The idea I have been toying with is to use Bobcat hydraulic motor on each wheel & a freewheeling hub each. plenty of grunt & very simple to engineer.
Hydraulic pump on pto - no brainer.

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Don,I have only a basic knowlege of hydraulic drives, but have you seen a schematic drawing of the LandRover Mayflower (MAP) hydraulic winch assembly? What a mess of pipes and fittings.And the capacity of the hydraulic oil tank, just to keep the oil at a reasonable temperature! And on a low geared wormdrive winch at that.
I'd imagine the hyd pump and wheel motors would generate a bit of heat, thereby requiring a sizable tank.
So let's see,you'll need a high volume PTO driven hydraulic pump, 2 hyd wheel motors plus special stub shafts and adaptor plates to fit free wheel hubs, 1 hydraulic oil supply tank, 2 high pressure feed lines from pump to wheel motors, 1 low pressure supply line from tank to pump and 2 return lines from wheel motors back to tank, possibly via an oil cooler. Then you still have to mount these wheel motors to an axle with special wheels.
What could be simpler:confused:
Bill.