The Stovebolt Site Forums The Parking Lot Big Bolts Gar Wood Dump Hoist

I savaged the cam and roller hoist, pump, pto, and transmission from a '41 Chevy 1 1/2 ton and installed it on my '36 1 1/2 ton. After months of cleaning, painting,bolting etc. the big day comes and I find out that the pto turns one direction and the pump pumps when it is turned the other direction. Hard to believe that the previous owner drove the truck all those years without being able to dump! Last ditch effort is to open up the pump in hopes that it is reversable. Could really use some advice on these pumps.

Some of the old pumps were reversable by removing the gear sets and turning the housing around. Others by putting top gear on bottom, etc. Still others had dual shafts which made the job much easier simply by putting the drive shaft on the opposite pump shaft. Not sure what GarWood did in those days.

If this doesn't do it you'll need to get a double gear PTO or a gear spacer which changes the rotation but requires additional space. PTO's are specified as either enginewise or opposite engine rotation.

Dave,
Thanks for that. My pump has only one exposed drive shaft and no visable way to reconfigure the pump. What I can't make sense of is that the pump is factory located on the drivers side of the hoist cylinder which is specific to Chevrolet and should be enginewise rotation but is not. I can't think of an application that would be drivers side with a ccw rotation!
David

David,

The hoist and the pump is manufactured with no specific chassis brand in mind. The rotation is determined by the transmission drive gear and has nothing to do with the pump or it's location. Also as I mentioned there were double gear PTO's avalable which changed the rotation of the PTO outout shaft if the powered equipment required something different. Also there were (are) forward/reverse PTO's used for driving 2 way equipment such as a mechanical winch.

Can the pump be relocated or is it a manifold mount, i.e., does it have hoses running from the pump to the cylinder or bolted onto a cast metal manifold?

If all else fails and your unable to locate a double gear PTO and if your pump is a hose type unit then you can always replace the pump with something more modern in either a twin shaft or bi-rotational style. If your like me and even if you never use it you still want it to work.

The pump is mounted to the cross frame at the front of the cylinder and is connected with formed steel lines. The pump feeds center top and the output manifold can be installed on either side of the pump depending on rotation. I could make a new bracket, valve toggle and base, cut steel line and weld on modern fittings, drill and mount etc. Working on buying a '41 dump for another set-up....

Dual outlet ports?

Have not opened the pump up but there is the same bolt pattern on both sides of the case. One port and one cover plate with same layout. My extra pump has the port on the other side. Dual outlet only in the sense that you could use one side or the other depending on rotation.

I had the same problem on my dump truck... I just turned over the pump.

http://bus-plunge.blogspot.com/2010/11/1st-trip-to-leaf-dump.html

I have a PTO unit that has two gears inside it. The gear that engages with the transmission gear is larger than the gear on the output shaft. The ratio is 1:2 (overdrive?)...for each turn of the gear that engages the transmission the output turns two times. The rotation of this unit is opposite when compared to a single gear PTO unit.

Maybe Dave can chime in and explain what I have...it came off of a SM420.

Mike B

It's nothing special frankly. All double gears are made that way. The larger gear is engaged to the tranny drive gear all the toime and the smaller gear slides in/off of it. Don't be too sure about the 2:1 drive. It is only the output shaft ratio that is important. They are all over the board, from way under the engine speed to way over it. There is a number on the side of the larger driven gear and that will tell you what it fits if you have the chart. They can be configured in a good many ways for left side or right side, shaft above ctr or shaft below ctr. Muncie, Chelsea, Spicer, Tulsa are the common ones. Only Muncie and Chelsea (now Parker Hydraulics) survives.

Thanks for the info Dave.

My point about the 1:2 ratio is the big gear turns 1 time and the little gear on the output shaft turns 2 times in relation to each other. How that relates to anything else is beyond me...

I do have other PTO's that came off of SM420's and they have the same size large gear directly connected to the output shaft (only one gear in the PTO) which would make the output shaft turn slower than the unit mentioned above.

Do some pumps require a higher rpm to work correctly?

Thanks again for your insite.

Mike B

I wish I could turn the pump over Jim but yours has two input shafts and mine only has one. After a couple of frustrating weeks of walking tight circles around the truck it looks like the next move is to fabricate a new bracket, port out the other side of the pump, and cut and weld the steel line from the cylinder to pump. The steel line could be replaced with modern fittings and hose but I want it to be right and original. I had bought another truck to get this whole setup and still can't believe that it was all installed on that truck and never worked!

dmart...I don't see where you've said what you tranmission model is. I don't know what was used in a 41' chev, maybe an SM420. If your tranny has PTO openings on both side that may be the answer you need. I doubt that it does frankly but always worth a try.

A picture of this thing would really help a bunch.

Dave,
I'm not that good with transmission models but mine is the standard 4 speed chevy box from the 30's-40's. It only has a pto opening on the drivers side. Working on getting some pictures posted.
David