Hydraulic vs. pto Winches

[Csm Davis]

Only thing is Ron I see way more of the lighter weight plates like 10 to 1 and it would back up me trying to pull a 931 tractor on flat ground that is covered in rocks and it tried to move but didn't. But thanks for the info on the pumps if I get the chance I will try the same move with the heavier rated truck. But this begs the question how's the wreckers get their self out of a bad spot?

 

[timothy11]

You get a tank or dozer

 

[m16ty]

I have a M936 rear winch on the way but if Jeff is right I may not be able to use it as intended. I've got a M816 rear winch mounted on my KW. It has been converted to hyd and will pull 45K or very close to it. The only problem is it's very slow. I was planning on swapping it out with the M936 winch to get the two speeds. If it won't pull 45K single line I can't use it. I use it to operate the neck on a M870 and with a heavy load it takes close to 45K to fold the neck.

Here's a pic of what I'm currently running.

 

[dburt]

Now M16ty, if I was your mom I'd scold you for the way that cable is wound up on your winch! Of course I'm not, so I won't- just saying if I was . . . . . .

 

[m16ty]

Now M16ty, if I was your mom I'd scold you for the way that cable is wound up on your winch! Of course I'm not, so I won't- just saying if I was . . . . . .

I figured somebody would comment on that when I posted the pic.
The problem is 3/4 cable is almost imposable to keep straight without the level wind. If you'll notice there isn't much cable on the drum. There is only enough to operate the neck on the m870 (I'd say less than 50'). We keep it short so it won't get balled up too bad. That's another reason I want the M936 winch. It still has the level wind on it.

 

[Csm Davis]

Well good news the actual winches are the same the weakness is in the hydraulics.

 

[m16ty]

The current winch I running is a hyd 45k line pull. I was hoping to get the two speeds of the M936 winch. I may just swap the level wind onto my current winch and leave it at that. I may do some testing on the M936 winch before I give up on using it.

 

[73m819]

Well good news the actual winches are the same the weakness is in the hydraulics.

So what I was told is true, thank you for letting me know , I was told the pump on the 936 is the SAME pump that is on the 816

 

[Csm Davis]

Not what I said

So what I was told is true, thank you for letting me know , I was told the pump on the 936 is the SAME pump that is on the 816

The winches are the same, I don't know if the pumps are the same, I have both winches only difference is the sprocket on the winches and how the chain is driven.

 

[Csm Davis]

By the way I don't know why the 936 winches would be so derated the motor on those is huge!

 

[73m819]

By the way I don't know why the 936 winches would be so derated the motor on those is huge!

The pump can not put out the volume, hence pressure for those BIG motors, I think it was a case of TWO different groups designing the 936 but not talking to each other since each had a job to do, One group set up the hyd winches, assuming that the existing hyd pump had enough push but not checking if it did, the other group mated the 816 bed to the 900 5t, assumed that the existing pump would have enough push for the rear winch because thay did not ask what the hyd motor needed, each group thought the other would provide the CORRECT half of the hyd system. Not till a 936 is born, do group 3 (testers) find that OOPs not enough push, so it was faster and cheaper to DEREAT the rear winch then do a RETRO FIT of a BIGER PUMP or DIFFERENT MOTOR.

Tax dollars at WORK

 

[Jakelc15]

Pump volume or gpm = winch speed
Pump pressure = winch power

The larger motor may need more pressure to put out the same torque s the smaller one.
I'd be interested to know the displacement of the pump and motor and the relief valve pressure setting.

I am going to mount one of these winches behind the cab of my tractor as soon as I find one.

 

[jasonjc]

Pump volume or gpm = winch speed
Pump pressure = winch power

The larger motor may need more pressure to put out the same torque s the smaller one.
I'd be interested to know the displacement of the pump and motor and the relief valve pressure setting.

I am going to mount one of these winches behind the cab of my tractor as soon as I find one.

Ture BUT you need the GPM at the PSI. If you pump puts out 10 GPM @ 2000psi and you pump needs 15 GPM @ 2000psi you are not going to get the full pull.

 

[Jakelc15]

2000 psi @ 10 gpm and 2000 psi @ 15 gpm is going to give you the same line pull just different speed.

I understand what your saying though. The only way to tell what pressure your getting at the motor is to put a test gauge in and load the winch til the relief valve opens.
The motor won't have full pump psi until stalled.
You are definitely right about the pump and motor not being matched properly. Have to match pressure to displacement to get the proper in. lb. of torque needed. Need to know the diameter of the winch drum and the winch gear ratio to figure out the motor torque needed.

 

[Recy Mech]

Good thread.

 

[m16ty]

Jeff, Where are you getting the winch ratings on the trucks? I just picked up my M936 today and the tag on the rear winch says 45K. Is there another data plate where you are getting these lower figures?

 

[Csm Davis]

data plates

Dataplate on rear of bed left of winch on storage tube of outrigger

 

[Csm Davis]

Okay got to pull a different wrecker with rear winch, worked great. It worked better than tagged. It was rated 25000 and 45000 blocked. So now I think I might want 936

 

[Csm Davis]

Okay have been going through lots of cable ratings lately and think I may have an idea on what's with the tags being different, the working load limit or wll on 3/4 16-9 hemp core wireline is NOT 45,000 or even close, so I believe someone is trying to cya and list the correct wll of 14,500lbs, fair warning the winch will out pull this and break the cable, on both the 936 & 816 the 45,000lbs that we see on the winches is what they are rated to pull not the cable.

 

[m16ty]

Okay have been going through lots of cable ratings lately and think I may have an idea on what's with the tags being different, the working load limit or wll on 3/4 16-9 hemp core wireline is NOT 45,000 or even close, so I believe someone is trying to cya and list the correct wll of 14,500lbs, fair warning the winch will out pull this and break the cable, on both the 936 & 816 the 45,000lbs that we see on the winches is what they are rated to pull not the cable.

I'll agree with that. I've got a 45K wrecker winch mounted on the back of a KW. It's hyd drive but the hyd motor is civilian and geared to pull the full 45K. I've broken the cable more than once folding the neck on a M870 with a heavy load on the deck.