Why is the warn Highmount so fast?

[Rockmonsta]

OK I might be asking the obvious but from how I see the 8274 and low mount are all electric motor single speed gearbox's to the drum. So if a low mount has the same gear ratio as the 8274 why the difference in performance? Is it because the highmount has a much more effecient drive train and no brake inside the drum to sap a bit of power?

Just thought I'd throw it out there, its been flying around in my head for a while now.

[stuee]

Would be put down to gear ratio and drum diameter.

edit* I just reread your post carefully and you've already cited gear ratio. Are you 100% they are the same?

[-Scott-]

I would guess that whole "brake dragging" thing could be an issue.

[Slunnie]

The gear ratios are not the same, the highmount is geared to pull faster.

I recall reading something somewhere about ARB being miffed as to why other winches were outpulling the Warns... and that was put down to brake drag.

[PJ.zook]

Would there be some kind of friction or ratchet mechanism built into it, so when there is no load on the line it winds in fast, but when load is applied it locks into a much higher ratio? Im only guessing but.

[chpd80]

Its simply gearing ratios, pull the 2 big gears out of the high mount and compare them the the small gears out of the low mount and you will understand why the high mount is so fast.

Same as your 1st gear high range is faster than you 1st gear low range.
The trade off for speed is less pulling power.

The beaty of the high mount although its only 8000lb (standard) is its fast enough to be able to drive with less risk of overrunning it and shock loading it.

[nzdarin]

It is simply a different gear ratio.
High mounts are 136:1 and have a 3.5" drum where as most low mounts are about 156:1 and have 2.5" drum. (9000lb)
The brake drag etc isn't a huge factor in speed as most of them are disengaged when under power so drag is minimal.
Overcoming the drivetrain is a factor and that is why any winch with a twin motor will go faster no load than a single. Even with the exact same motor.
Just as an idea most of the electric motors will spin at 10,000rpm without any load. The gear train provides a load so reduces the effective no load speed.
My Superduty 7.8hp 24v motors are factory tested and spin at 10,000 in one direction and 10,400rpm in the other. But this is with nothing at all on them and just in atest rig. Fit them to a winch with either planetary (low) or spur (high) gears and there quite aload for them to overcome.

For a 12k winch the ratio goes up to about 260:1 and for a 15k it goes to about 315:1.

[Rockmonsta]

Ok, so why not gear a low mount, M8000 for instance, to 134:1 ?

[85lux]

these comments are for the "no-load" circumstance

it is the brake drag.
a dc motor with no load will spin itself faster and faster until it self destructs, unless it is slowed by a gearbox or some external factor(or friction in bearings).
also, a DC motor makes high torque at low rpm and its torque decreases with rpm. so it does not take much to slow the motor down when at high RPM

when a high mount spools in, the spur gears have very little friction, the brake partially locks up on itself, but the brake ratchet simply allows the brake assembly to spin, preventing it from slowing the assembly down.

most low mounts are different. they have a brake assembly which is direct driven from the winch motor. this brake attemps to "unlock" itself when winching in. however although unlocked, there is still a bit of friction in the brake(considder the speeds you are trying to spin this brake assembly at when it is direct driven from the motor.).
this friction radically slows down the top speed or to use an incorrect term, terminal velocity of the motor.


as explained above, it is the brake dragging that slows the no load line speed of a low mount down.

jim

[Rockmonsta]

Uh Huh!

Thanks, Nice car car by they, although the springs look a bit stiff....

[sudso]

Ok, so why not gear a low mount, M8000 for instance, to 134:1 ?

I dont think there are gear ratio's that tall for a low mount. The motor would overheat pretty quick under load and the little gearbox in them wouldnt handle the load with that ratio.

[stuee]

From warn website:

http://www.warn.com/truck/winches/src/M8000.shtml
M8000 gear ratio 216:1
Motor: 12V 4.8 hp, 24V 2.1 hp

http://www.warn.com/truck/winches/src/M8274-50.shtml
M8274-50 gear ratio 134:1
Motor: 12V 4.6 hp/3.43kw or 24V 2.5 hp/3.43kw

Gear ratio is not the same.

[sudso]

From warn website:

http://www.warn.com/truck/winches/src/M8000.shtml
M8000 gear ratio 216:1
Motor: 12V 4.8 hp, 24V 2.1 hp

http://www.warn.com/truck/winches/src/M8274-50.shtml
M8274-50 gear ratio 134:1
Motor: 12V 4.6 hp/3.43kw or 24V 2.5 hp/3.43kw

Gear ratio is not the same.

The high mount motors might have heaps more torque as well even though the hp ratings are similar. Something to do with the windings.

[Bush65]

The grease lubricated multi-stage planetary gear unit in low mount winches are designed to a low price, not to be efficient.

The bearings for all of the rotating parts (of which there are many more than in high mounts) are very poor as far as friction goes.

The planetary unit has many more teeth in mesh compared to the high mount and each produces drag.

IMHO low mounts are power hogs.

[me3@neuralfibre.com]

The grease lubricated multi-stage planetary gear unit in low mount winches are designed to a low price, not to be efficient.

The bearings for all of the rotating parts (of which there are many more than in high mounts) are very poor as far as friction goes.

The planetary unit has many more teeth in mesh compared to the high mount and each produces drag.

IMHO low mounts are power hogs.

Easy to tell - does a low mount gearbox get hot?
With 1.5-3kw going through it, a 20% loss (300-600 watts) will get pretty hot pretty quick.
If it's not going to heat, then it's not going to friction, and it's not losing much.

Paul

[-Scott-]

From warn website:

http://www.warn.com/truck/winches/src/M8000.shtml
M8000 gear ratio 216:1
Motor: 12V 4.8 hp, 24V 2.1 hp

http://www.warn.com/truck/winches/src/M8274-50.shtml
M8274-50 gear ratio 134:1
Motor: 12V 4.6 hp/3.43kw or 24V 2.5 hp/3.43kw

Gear ratio is not the same.

Me thinks there is a problem with their figures.

3.43kW is more like 4.6hp than 2.5hp.

[-Scott-]

a dc motor with no load will spin itself faster and faster until it self destructs, unless it is slowed by a gearbox or some external factor(or friction in bearings).

Sort of.

A DC motor is also a generator. As it spins, it generates voltage proportional to speed - but this voltage (typically referred to as "Back EMF") works against the voltage which is causing it to spin.

As the motor spins faster the Back EMF builds, and less voltage is available to keep the motor spinning. Even without friction in the bearings there will be a (theoretical) maximum speed which a DC motor can reach - when the Back EMF equals the drive voltage.

In the real world, as 85lux noted, bearing friction is typically the dominant factor in determining the maximum no-load speed - or some motors are simply not designed to run at their maximum no-load speed, and will self-destruct.

I used to work with an engineer who told me about a product he helped design. They needed a small fan to quickly produce a large "pulse" of air. They worked with a motor manufacturer, and ended up using a 12V (24V?) motor pulsed with 70 something (?) volts - and ran it to something like 5 times it's normal "no-load" speed. But, because it was intermittent and short duration, the motor coped.

[GUte]

The Warn 9.5XP at 156:1 ratio, 6hp, has the fastest line speed under load of any of the Warns.
The M8274-50 at 134:1 ratio, 4.6hp, has the fastest no load line speed of the Warns.

Al.

[dumbdunce]

a dc motor with no load will spin itself faster and faster until it self destructs, unless it is slowed by a gearbox or some external factor(or friction in bearings).

Sort of.

A DC motor is also a generator. As it spins, it generates voltage proportional to speed - but this voltage (typically referred to as "Back EMF") works against the voltage which is causing it to spin.

As the motor spins faster the Back EMF builds, and less voltage is available to keep the motor spinning. Even without friction in the bearings there will be a (theoretical) maximum speed which a DC motor can reach - when the Back EMF equals the drive voltage.

have a look at series wound (universal wound) motor theory. the induced EMF in these motors is in the same direction as the driving EMF, and in theory a series wound motor run without load will continue to accelerate as long as voltage is applied.


have you ever connected up a starter motor to test it and just let it run? the speed continues to build for quite some time after the initial spool up.

[nzdarin]

Has anyone noticed that a M8000 has a 4.6hp and 216:1 and is rated at 8000lbs. An 8274 has a 4.6hp motor and 134:1 but is rated at the same 8000lbs. In the real world even at a lower ratio it will still pull harder than a M8000 as well.
So how can the same HP with worse gearing produce more power at the drum other than the gear train being more efficient?

[-Scott-]

have a look at series wound (universal wound) motor theory. the induced EMF in these motors is in the same direction as the driving EMF, and in theory a series wound motor run without load will continue to accelerate as long as voltage is applied.

Got a link? It sounds like perpetual motion to me.

have you ever connected up a starter motor to test it and just let it run? the speed continues to build for quite some time after the initial spool up.

Can't say I have - but the only ones I've ever looked at have been permanent magnet motors.

[dumbdunce]

have a look at series wound (universal wound) motor theory. the induced EMF in these motors is in the same direction as the driving EMF, and in theory a series wound motor run without load will continue to accelerate as long as voltage is applied.

Got a link? It sounds like perpetual motion to me.

have you ever connected up a starter motor to test it and just let it run? the speed continues to build for quite some time after the initial spool up.

Can't say I have - but the only ones I've ever looked at have been permanent magnet motors.

google it up
http://www.gizmology.net/motors.htm
doesn't seem quite right to me buy hey, uni was almost 20 years ago, and I passed that subject with exactly 50%.

[-Scott-]

google it up
http://www.gizmology.net/motors.htm
doesn't seem quite right to me buy hey, uni was almost 20 years ago, and I passed that subject with exactly 50%.

I did.

Will definitely "run away" under no-load, and I can see that speeds could easily exceed the abilities of the physical construction. But speeds aren't "unlimited".

Under no-load current will decrease as back-emf increases. But, because of the series winding, the field strength decreases with current, so the back-emf won't increase linearly with speed. Makes it more difficult to determine where the ultimate (theoretical) limit would be, and, as you pointed out, will generally be somewhere beyond the point where it destructs.

Not something I'd ever really thought about before - so I've learned something new.

[beinthemud]

Because they can fit a bigger mouse in them which spins the wheel faster