Thread: Winch Selection Advise

Originally Posted by chook73

And here I was thinking you were getting sick of winching me up hills



Any feedback about a winch you have owned, fitted and worked at some point on a car that actually drives is useful……….



Ok a bit of a dub question but how do the manufacturers actually get the winch rating and what does it refer to if its not a WWL or a SWL? How does a 12,000lb low mount then compare with a 8,000lb low mount in terms of a meaningful comparison or is that just unrealistic.

From what I can tell the manufactures don't state how they come up with the rating they print on the box/packaging. So what can be deduced from their specs?

Before I get to that, understand that power, as applied at the rope winding onto the drum is (here I have called this Winching Power):

Winching Power (kW) = Rope Pull (KN) x Rope Speed (m/s).

Motor Power (kW) = Winching Power (kW) / mechanical efficiency

The difference between the two powers is mostly energy lost as heat. The mechanical efficiency of typical low mount winches is dreadful, so more of the motor power is consumed as heat.

So if we want a greater Rope Pull, for the same Motor Power, we have to reduce Rope Speed. This requires a greater gear reduction.

The same conclusion can be reached from:

Drum Torque = Rope Pull x [(Drum Diameter + Rope Diameter) / 2]

Motor Torque = (Drum Torque x Gear Reduction) / mechanical efficiency

Motor Power = 2 x pi x Motor Torque x Motor Speed

Note: I didn't give the units of measure, but they just need to be consistent.

It was some years ago that I compared the specs of different winches, and the variety has increased since then. I believe the manufacturer's rate their winches on rope pull from the bottom layer of rope on the drum. The link between rated pull and reduction ratio was apparent across the models I looked at.

You could recast the equation for Motor Torque above as:

Winch Rating x Gear Reduction = Constant (approximately)

or:

Winch Rating = Constant / Gear Reduction

Drum diameter of these commercial vehicle winches is based on standard pipe outside diameter, it is the same for most low mount winches, but the high mount drum is based on the next larger pipe diameter. They all use a drum diameter that is too small for the wire rope, and this reduces the strength and life of the wire rope - high mount drum diameter is better. Bending the rope around a drum increases the load in the outer wires (fibre) of the rope. In the case of wire ropes bent around drums or pulleys there are two ratios that should be taken into consideration:

Drum Diameter to Outer Wire Diameter (with small drums we need smaller outer wire diameter, this gives a more flexible rope with a larger number of wires, but wear is worse).

Drum Diameter to Rope Diameter (small drums need small diameter ropes, and lower breaking strength).

However increasing the drum diameter for the high mount reduces the rope pull, but the rope speed will be higher for the same drum speed or reduction ratio.

Rope diameter, and breaking strength is going to play a part of the selection. Most of the common low mount winches come with a larger diameter rope than the high mount, 3/8" vs 5/16", however the rope is easy to upgrade on a high mount.

Originally Posted by Redback

Here ya go chook, Warn High mount
Warn High Mount Winch | eBay

Personally I think Warn winches are over rated, most of the other brands of the same quality are much cheaper, but hey, to each their own.

Baz.

The add says that this has a 2.5hp motor however all of the other warn high mounts I have seen come with a 4.6hp motor. Were there 2.5hp versions or is this more than likely a mistake?

Originally Posted by Bush65

From what I can tell the manufactures don't state how they come up with the rating they print on the box/packaging. So what can be deduced from their specs?

Before I get to that, understand that power, as applied at the rope winding onto the drum is (here I have called this Winching Power):

Winching Power (kW) = Rope Pull (KN) x Rope Speed (m/s).

Motor Power (kW) = Winching Power (kW) / mechanical efficiency

The difference between the two powers is mostly energy lost as heat. The mechanical efficiency of typical low mount winches is dreadful, so more of the motor power is consumed as heat.

So if we want a greater Rope Pull, for the same Motor Power, we have to reduce Rope Speed. This requires a greater gear reduction.

The same conclusion can be reached from:

Drum Torque = Rope Pull x [(Drum Diameter + Rope Diameter) / 2]

Motor Torque = (Drum Torque x Gear Reduction) / mechanical efficiency

Motor Power = 2 x pi x Motor Torque x Motor Speed

Note: I didn't give the units of measure, but they just need to be consistent.

It was some years ago that I compared the specs of different winches, and the variety has increased since then. I believe the manufacturer's rate their winches on rope pull from the bottom layer of rope on the drum. The link between rated pull and reduction ratio was apparent across the models I looked at.

You could recast the equation for Motor Torque above as:

Winch Rating x Gear Reduction = Constant (approximately)

or:

Winch Rating = Constant / Gear Reduction

Drum diameter of these commercial vehicle winches is based on standard pipe outside diameter, it is the same for most low mount winches, but the high mount drum is based on the next larger pipe diameter. They all use a drum diameter that is too small for the wire rope, and this reduces the strength and life of the wire rope - high mount drum diameter is better. Bending the rope around a drum increases the load in the outer wires (fibre) of the rope. In the case of wire ropes bent around drums or pulleys there are two ratios that should be taken into consideration:

Drum Diameter to Outer Wire Diameter (with small drums we need smaller outer wire diameter, this gives a more flexible rope with a larger number of wires, but wear is worse).

Drum Diameter to Rope Diameter (small drums need small diameter ropes, and lower breaking strength).

However increasing the drum diameter for the high mount reduces the rope pull, but the rope speed will be higher for the same drum speed or reduction ratio.

Rope diameter, and breaking strength is going to play a part of the selection. Most of the common low mount winches come with a larger diameter rope than the high mount, 3/8" vs 5/16", however the rope is easy to upgrade on a high mount.

Thanks John as always a mind boggling overload of information which will take a few reads to get my head around………….

Whilst your calculations are great getting the information to do the calculations is not always possible it seems so for the laymen like me the load rating of a winch seems to be little more than a rough guide indicating the overall efficiency of the winch………

Is there anything like drum brakes on the high mounts which would prevent the use of dyneema?

Hi-Mounts came with the little 2.5HP motor, but many have been upgraded with 4.6HP or 6HP motors, which bolt straight on, though some need a different pinion gear due to different motor shafts. Mine has a 6HP motor by memory. Clubagreenie may recall...

There is no reason not to run Dyneema on a Hi-Mount due to heat. The brake is on the opposite side of the gearbox to the drum, so plenty of seperation there. The motor is also away from the drum, so both heat sources are away from the drum. Being a larger diameter drum than a low mount, as John said, it will 'look after' the cable/rope better than a low mount too.

Originally Posted by chook73

The add says that this has a 2.5hp motor however all of the other warn high mounts I have seen come with a 4.6hp motor. Were there 2.5hp versions or is this more than likely a mistake?

The original 8274 was 2.5hp
The 8274-50 was fitted with the 4.6hp
The very limited edition 8274-60 was fitted with the 6hp xp motor

The 6hp motor is a straight swap onto any fitted with the 4.6hp (99% sure)

Earlier winches require the gear swap as mentioned above

Mine was a 4.6, and is now a 6hp

As above, the 2.5 has a keyed motor and input gear, all other motors have a splined shaft/gear. Mark, yours has a 6hp and splines with new gear and yes, the brake is a disc and pad type. Great setup just needs cleaning to keep the mud out.

You can also fit the bowmotors to the warns but need an adaptor plate as there's something different about the mounting face.

Originally Posted by chook73

Thanks John as always a mind boggling overload of information which will take a few reads to get my head around………….

Whilst your calculations are great getting the information to do the calculations is not always possible it seems so for the laymen like me the load rating of a winch seems to be little more than a rough guide indicating the overall efficiency of the winch………

Is there anything like drum brakes on the high mounts which would prevent the use of dyneema?

The load rating doesn't indicate efficiency, it simply the manufacturer's rating for how much tension the winch can apply to the rope (rope pull).

Efficiency is the ratio power out / power in where power out is (rope pull x rope speed) and power in is motor power. Power is lost between the motor and rope due to friction. If youprefer you could replace power with energy for the same outcome. Energy out becomes (rope pull x distance) and energy in (motor current x time).

The real guide to efficiency is how the winches perform under load. "How much" and "how far" they can pull for the same amount of input energy.

The input energy is hardly an issue for hydraulic or PTO winches since they have an abundance of power/energy available (if the engine is running).

With electric winches besides the obvious limitation of the battery and alternator capacity, is the energy lost due to heat generated due to internal resistance in the motor. As the motor gets hotter, the resistance increases, so the current increases making the motor hotter ...........

For a short or easy recovery, the heat loss in the motor is small enough, and the mass of the motor is great enough that it absorbs the heat for only a small increase in temperature. It is when the winch has to work harder for longer that you find which winch is better, and which are an ornament/burden on the front of your vehicle. The motor output can easily halve when it gets hot.

The more efficient the winch, or the more powerful the motor, the lower the current (for same rope load) and the less the motor heats up.

The grease packed, double reduction planetary gear sets of low mount winches generate a lot of friction though the large number of moving parts and the poor bearings (due to small size of the gears).

The Mile Marker (or Ox) hydraulic winch has a single reduction planetary gear set, which is better made than what I have seen inside a Warn low mount - they are the best made of any low mount winch I have seen the insides of.

The oil lubricated spur gear set in the high mounts are significantly more efficient than the low mount winches.

Worm gear sets in PTO winches are very inefficient, but they have an abundance of power so it doesn't matter. It is because of the friction in the worm gear set, that they don't need a brake - the worm friction will hold the load (the higher the load the higher the friction, which also applies when talking of friction for the other winches).

Hydraulic winches can use the hydraulic system to hold the load when not winching and don't require a brake. There are different methods, but an overcentre valve is the best solution.

The old Bellevue high mount winch has an external drum brake, the Warn high mount has an external disc brake. These brakes act on the final reduction pinion shaft so the braking torque at the rope drum is, IIRC, six times the braking torque at pinion shaft. Neither create any heat in the rope drum.

The heat problem when using synthetic rope on low mount winches is not heat generated when winding in rope or when the brake is used to hold the load. The heat in the drum is generated by the brake when the rope is wound out against the brake - effectively driving with the brake applied. This doesn't apply for winches that have the brake external to the drum.

Brakes on vehicle winches are applied automatically and only release while rope is being wound in. Most have a free-spool device so the rope can be pulled off by hand while the brake is applied, but it is 'easier' to power out rather than use manual effort, especially when the rope wasn't spooled on neatly during the last recovery.

Hmmm, interesting thread. Having just posted a thread in the 'Non Land Rover Technical Section' asking about Runva Hydraulic winches, I then find this thread. Re 'Which Winch', years ago I was involved in UK Rally Recovery, and Warn Winches were the go! There were lots of Top Mounts. We then changed our setup to a rear under floor mount hydraulic winch as it suited us better. That was unstoppable which is why I want to fit one under the rear of the 101, especially as it'll counter balance the large boat anchor up front! No one has mentioned Superwinches. Are they any good??... Anyone had anything to do with the Runva winches?? The price ($1350 on Ebay) makes them affordable for sure... and the so called 'lifetime guarantee' also makes for a good buy....