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PTO & drive assist?


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Yes

er

and No :lol:

There is nothing to stop you driving and winching at the same time

except

mech and Hyd PTOs do not really like high RPM (my winch is around 1500 rpm for full pump output - speed of the winch is then interlinked with the gears 1 2 3 4 5 - rev via spool block reverse not rev gear), and heres the problem

The winch will pull at a certain speed, the wheels will equally turn at a certain speed dependant on gear and rpm, but neither can be adjusted so that wheels and winch work at the same speeds.

ie you may find the drive is faster than the winch, rope drops to the ground, LR slides back and cable gets a huge twang...not good clever for anything in the winch train inc the rope.

The trick for driving and winching on PTO winch is reading ahead, and being able to correctly enagega nd disenage drive while keeping the winch cable tight.

Many have tried matching the PTO / motor pump to ensure matches with wheels, but then clearing a hole ad sliding due to driving and even then getting the match has made it tricky - bear in mind all electric winches sppeds increase when no load, so they can take up the slack when no load very quickly.

Drive assist was initailly done to suplement winches and reduce the loadf and drain on batteries etc, and whilst this is true the more powerfull and more modern electric winches have reduced this need massively - but DA also gives you ability to allow slight movement and positioing of your LR but doing it, whereas no drive asisst makes positioing of the LR a nightmare,.

so, yes it is possible, very very very difficult at best and at worst a nightmare !

Superfast pumps on hyd help...hence why I am currently on the last knockings of an upgarde to mine...even so it will never drive assist as well as a decent leccy unit

HTH

Nige

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I get what you are saying Nige, however can one not use a manual spool valve to adjust the winching speed, and *potentially* match it to that of the driving speed?

Prob not as you need MORE speed not less.

ie if its winching but driving slower than the winch is pulling - no problem, full speed ahead,

but as soon as the wheels find traction, the load on the winch drops, but the speed DOES NOT increase (which it WILL on leccy as the load has dropped...)

nige

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You can achieve similar things with clever hydro pumps and/or motors, variable-vane pumps increase their output as pressure drops, you can get motors that do similar, EG speed up when load is low. They're money but I was quoted £700 for a VV pump (it was a very rough quote from a hydro place and they could well have been quoting for something way too big as they're used to HGV's). Doesn't look so expensive when you consider twin-motoring an 8274...

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How about crank driven (not PTO) pump + manual spool + autobox (torque convertor)?

Should give a good control (of the balance) between max torque put to wheels and torque put through winch line.

Can you get proportional control solenoids / servos for hydraulic valves? (something similar to large R/C servos) that would avoid having the valve block in or near the cab?

Edit to add: In addition to what HFH said, drive assist is also useful for getting the front wheels up and on a large step obstacle (especially if it is greater than half the height of the front wheels) given a straight ahead pull

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Crank driven is a possibility - itll be on a TD5 though and as far as i know its not been done yet so no-one to copy!!! :rolleyes:

I do plan on it being an auto, that however may not be in its first build due to cost of auto's for td5's.

As for in cab spool valves/blocks - what is the problem with these, yes hydraulic fluid under pressure can be lethal but just think most plant machines have in cab valves/controls and you dont hear of problems with them and its essentially the same here :)

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Let the maths talk you through it……………… :)

88ft/min = 1 mph

My pump will be at max flow when turning at 2500 rpm ……….. which will turn the winch at 45 ft/min ……. And that is just fractionally over 0.5 MPH

Remember that the PTO is driven through the gearbox (assume LT77S) , so to get the pump turning @ 2500 rpm the engine rpm will be,

1st = 9000

2nd = 5275

3rd = 3200

4th = 2500

5th = 1925

Assuming Std 3.54 diffs, 34 inch tyres and std low range gearing, then the wheel speeds are,

1st =5.975 MPH

2nd = 10.175 MPH

3rd = 15.350 MPH

4th = 21.475 MPH

5th = 27.9 MPH

So to keep the revs reasonable you would winch in 3rd or 4th gear……….. therefore the winch is recovering line at 0.5MPH and the wheels want to turn at 15.35MPH best case or 21.475MPH worst case …………. either way, that tends not to work too well. :rolleyes:

Ian

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