Winch choice - 24v electric or hydraulic?
 

Having finally got the base vehicle (Merc 917 4x4) - I need to make some pretty quick decisions on the fit out. I have a mate who runs a wholesale winch business and will do me either a 5 ton hydraulic winch or a 7.5 ton 24 volt one for £500 - list price about £1200 on both.
He and I both agree that the hydraulic is the better piece of kit and likely to last longer. But a hydraulic winch wont run if the engine stalls! (river crossing etc.). Providing the batteries are ok the 24v one will pull out a stalled vehicle.
Any thoughts?
Steve

Winch
 

Had the same idea!. By the time I winched it out the winch had used enough of the battery, it would not crank the engine. But at least I was out and could work on dry land.
Norm

Both winches you mention would be a tad light for a vehicle rated at about 10 tonnes GVM. I know you can double or quad the cable but that means carrying a lot more recovery cable to hook onto something. It also means running the risk of really rooting up the winch gearbox. Plus the safety issue of pulling a 10 tonne vehicle on cable probably only rated at twice the safe working load of the winch eg 5 tonne winch = 10 tonne cable?

I'd be Googling on winch selection to vehicle GVM or having a look at what ever the Armed forces use for their 8 to 12 tonners. Usually the selection process goes something approximately like;

1. Vehicle GVM
2. Winch capacity exceeds vehicle GVM
3. Mounting to vehicle capacity exceeds vehicle GVM
4. Cable capacity exceeds GVM - I think there is a sliding scale used for cables its not just GVM = 10 tonne therefore cable capacity is 20 tonne.

Choice is then based on the winch surpassing all the above. Buying a 5 tonne winch for a 10 tonne vehicle will only leave you stranded sooner or later, and maybe in a worse condition if the winch fails dangerously.

PTO winches are by far the best way to go on a diesel engined vehicle as stalling them due to water around the engine is not a problem (unless you have leaky or low mount air intake system in which case it can be fatal for the engine). Mercedes provide a PTO for the 917 so a winch would not be hard to come by - but at UKP500 unlikely.

Electric winches on petrol vehicles are usually fine, especially if you have a leisure battery fitted to isolate the engine battery from the "leisure items" - winch, fridge, vibrating bed, etc.

What he said....

A winch is a serious tool, not a toy. It can both save you and kill you. The normally recommended winch pulling capacity is 'double' the vehicle weight. The winch capacity is rated on the first layer of cable, not just whatever length you decide to use at the time.

Elec winch users should install dual batteries, if they might encounter heavy winch use.

PTO winches can easily overload a cable and snap it if you don't know how to use one.

My personal opinion of hydraulic winches that run from the power steering pump is poor. They suck bigtime.

Understand the safe use of pulley/snatch blocks and anchoring them.

Vehicle recovery is cool and can be fun if you understand it, otherwise it can be dangerous.

Winch choice
 

I'm definately with Roman on this one - specially once you are talking about this size and weight of vehicle.
I would be looking at a 20 tonne rated winch and the appropriately rated cable - probably the one the military use.
Try Withams or Blanchards - they sell off ex-military vehicles and will possibly have them in stock.

Chris

Thanks for all the useful info guys, the vehicle is only going to come out at around 7.5 - 8 ton but I hear what you say. I can order whatever I like from my mate so I can go for 15 - 20,000kg no probs, I'll still get a big discount off the list price.
PTO it is then :thumbup1:
Steve.

I forgot to mention the PTO Capstan winch - not great for recovery but really great to turn a camel on a BBQ spit!!

Get some serious training with your winch, what you can get away with a softroader 4x4 and a winch you cant with a vehicle weighing 7.5 tonnes.

I think that Merc also provided a mid mount PTO winch which is great as it allows you to spool the cable out front or rearwards - pulling out backwards is often a better choice than pushing on into whatever has you bogged down. Whether it would suit your chassis I dont know.

Thanks mate, I'm happy with the 'use of' - used to own a small shipyard with a 1200 ton pneumatic winch and a Leyland Matador recovery lorry converted to 80 ton straight line pull. We used it to haul fast catamarans up a 1 in 8 slipway on 'greasy ways'.
I used the above to calculate the winch size (on the slipway you can pull LARGER than the winch rating) but of course I didn't allow for the vehicles being bogged down. Should have read up on it first as usual :innocent:

:thumbup1: Steve

Just a couple of points about winches, perhaps especially applicable to heavier vehicles:

1) Don't get too hung up on the "problem" of a winch not working when the engine isn't running. The only situation where that is even vaguely an issue, is the "stuck-in-a-raging-torrent" scenario. And in that situation, the advantage of an engine-free electric winch is in any case dubious at best (assuming you decided to drive into water deep enough to drown your engine, without another vehicle to assist). I wouldn't like to rely on a (probably submerged) electric winch, drawing 400A or more, to pull my vehicle clear without drive-assist and without an alternator feeding it.

2) A relatively low capacity winch is ok, if you carry good rigging equipment. With 3 heavy-duty snatch blocks and a heavy-duty extension rope, you can get (nominally) 6 times the winch's rated line pull. It's slower than using a higher powered winch, but just as effective, and perhaps more versatile. (Just remember that if you "daisy-chain" the snatch-blocks, then the blocks, shackles, and ropes must be rated for the actual load, not the winch's rated load!)

3) Use (good) synthetic rope unless cost absolutely rules it out. Wire rope is more difficult and dangerous to use and rig.

4) The strength of the rigging hardware (shackles, mountings, and blocks) is more important than the strength of the rope (unless it is steel cable). A synthetic winch rope breaking is pretty harmless, whereas a broken towing eye being catapulted through the windscreen is a diffrent matter.

5) Don't be tempted to use a winch on its own as a lifting device. That includes pulling a load (your vehicle, for example) up an incline, unless the brakes can hold it in the event of a failure. Or unless you have a secondary way of securing it if something breaks, such as a secondary rope, mounting point, and anchor. ("Tail" the secondary rope in as the primary rope is pulled in by the winch. If the primary rope/winch/anchor/mounting breaks, the secondary rope system will take up the strain, and prevent the vehicle tumbling down the slope).

6) In an expedition or professional context (as opposed to recreational off-roading), needing a winch is likely to involve a long period of fairly continuous use. This is really when engine-driven winches - mechanical or hydraulic - come into their own. Electric winches are fine for quick-and-convenient assistance, but they quickly show their weaknesses when they are called upon to do several hours work at a stretch. Generally unsuitable for heavy vehicles, but ideal for ATVs...

7) The maximum line-pull of PTO and hydraulic winches is usually well regulated by shear pins and relief valves. But beware of electric winches which exert peak strains on the rope at stall. Not only can they burn out themselves and parts of the electrical system, but they can put a dangerously high shock load on all your rigging. Stop and re-rig the winch if you hear it getting close to stall!

My comments above are not about electric vs mechanical/hydraulic winches in general - only about their relative suitability for expedition use, especially for heavier trucks.

Rgds,

Michael...