M51 A2 dump truck w/winch problem PTO and controls for winch and dump hydraulic pump

[Robo McDuff]

Actually, I hope I don't have a problem, but cannot get things back together.

About 10 years ago I made this truck into an M51 - M52 switchable dump-tractor truck.

To do so, I disconnected the drive shaft to the pump for the dump hydraulics and also the connections between the controls in the cabin and on the pump. Since then, I did not do anything with that system: the dump was disconnected and the Garwood winch was already kaput.

I now tried to put everything together but cannot connect the rear shifter shaft to the pump. Also, the Dump control lever to raise or lower the dump does not work as should be. Probably it is a question of trying it with the engine on, but I do not want to destroy everything; better ask here first.

1) The PTO control lever in the cabin has three positions: down-front, up-dump, neutral (which can be locked). This works with the transmission mounted PTO (
a) I cannot really get this lever in the utmost up or down position. Also, when as far up as possible, the rear output shaft to the pump still does not engage with the engine.
b) The rear shifter shaft does not come backwards enough so I cannot connect the linkage between pump and shifter shaft. Edit to clarify: the shifter shaft comes backwards rotating the next part of the link forward. The link still connected to the pump is also sticking forward. It can move about 1/2 inch forward and backward, but even in the best position, it is still about 1/2 inch further forward than the link to the shifter shaft, so I cannot connect the two.

2) The hydraulic pump is regulated from the control lever in the cabin, inside the cabin to the left behind the driver. This lever should have four positions: Neutral (lever straight up) - down - hold - up. The lever is connected to the pump. I think I get to the hold position, or somewhere between down and hold, but definitely not further down. Does not feel like a stuck spongy feeling but a hard block somewhere.


Edit: the rear output shaft from the PTO is connected to the pump and the PTO. I can turn the shaft by hand both directions without problem. Not sure if this is because the pump is in neutral or engaged and rotating without problem.

Any idea?

Starting the engine and with everything in neutral carefully trying to shift the PTO lever?
As said the output shaft is connected to the pump and I can get the dump control lever in neutral, so hopefully trying this with the output shaft connected will not wreck the pump. Or should I disconnect the shaft?










1

 

[country]

These dump control boxes pose alot of issue

have you tested it?


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[Robo McDuff]

How do you test it?

The lever on the controller that links to the rear shifter shaft can be moved forward and backwards some space, but it does not feel like its shifting something, just free space. Then it "clacks" against a stop, at least that how it feels when moved by hand. The one linked to the dump up-down controller is harder to move. Could not move it by hand, but with the complete linkage in place, from controller to lever in the cabin, it was able to move at least from neutral to down and hold, but not further.

Should it go easier if the engine is running powering the pump?

 

[BEASTMASTER]

when u say the dump lever goes up and down. on my m-51 the dump lever stands straight up. when in the hoist position, all the way towards front, which is straight up, you can't get out of the truck, because the handle is right at you're hip. one pos. back is hold, next pos. back is press. down, all the way back is gravity down. hoist pos. is easier to get in if the truck is running. good luck

 

[Robo McDuff]

This is as far forward - down position I can get the dump bed control lever.



The PTO attached to the transmission. Turned out that the winch really was completely frozen. I removed the front power shaft to the winch, but still could not get the winch side output (top red arrow) free and the hydraulic pump side engaged. The shifter rod (lower red arrow) is completely withdrawn, meaning the front output is engaged.





1) shifting rod or whatever you call it. Completely outward to the back. No matter if I put the PTO control lever in the cabin up, neutral, or down, this rod did not move enough to disengage the winch output. I made a scratch on the frame to check position, here seen between close to the tip of the arrow and the rubber protection around the shifter rod.

2) lever between shifting rod and cabin PTO lever.

3) rear shifter shaft going to the left side of the hoist control box

4) rear output shaft to dump hydraulic pump.

...

I finally used a crow bar to push the lever (2) forward, which pushed the shifter rod in. Note the location of the rod compared to the scratch mark
in this and the previous picture. The front output was more or less free, but the rear output still not fully engaged. A picture also of the position of the PTO control lever in the cabin.




Same numbers as above.
5) The link lever from the rear shifter shaft to connect with the control box. I used the crowbar again to push this lever a bit forward, to get it to fit the connecting rod coming from the control box.

All the pushing, the front output finally had come free, and the rear output fully engaged. Now the last problem: linking the shifter shaft to the control box.



6) the connector rod to the shifter shaft, hanging from the right side of the control box
7) the connector rod to the dump hoist control lever in the cabin
this connection I disconnected when removing the dump bed including the sub frame with pump and reservoir.
9) control box
10) hydraulic pump



Pushed 5 as far forward as possible, and 6 as far backward as possible (with not too much crowbar power). Still not possible to connect. Also, I am pushing 6 to the right side, but it will not go further to fit underneath 5. Probably the rod or the whole construction was bent sidewards while removing and putting back the sub frame on top of the main frame. Linking at # 8 previous pic was not a big problem.

Is it normal that when pushing - pulling the rod # 6, at a certain point the dump hoist linkage starts to shift also?
I would expect that these two are independent.

Any reason why I cannot get that last 1/2 inch room to connect the two?
I am afraid to put too much power with a crowbar. Maybe its time to start the engine and try again.

One thing I don't understand. I cannot get the rod 6 further backwards. However, lever 5 is as far forwards as possible, and is in the engage position. If I would put the cabin PTO lever in Neutral, the link 5 would come even more backwards, which would force the rod 6 further backwards, which I cannot manage manually even with reasonable force.

 

[BEASTMASTER]

what I think I see is you're winch control lever is near the floor ?? is it like that with the safety latch engaged?? something looks off . .what I do regularly is squirt all the pivot points with old motor oil, besides hitting the grease fittings. don't know if I'm being much help, or just confusing you more. wish u good luck

 

[Robo McDuff]

Safety latch is open; you can see it laying away from the lever, still wet from several treatments of WD40



Don't forget, the dump truck PTO lever works different from the standard cargo versions. THe dump truck has an up position for front winch and down position to engage the hoist hydraulic pump.

 

[Robo McDuff]

Finally found a good linkage scheme for the M51.

TM 9-2320-211-20-2-2 page 385 - 368

Just will put it here to make it easier

...

That section has good description as well on page 392 and 394.

Seeing the pic on page 392, it looks that my dump control lever is going as far as it should; I have in my memory that the different positions were much farther apart.


TM 9-2320-211-34-2-3 has some clear pics as well on page 262 and further. Below a better close-up of the hoist control box with the hoist hydraulic pump and the connecting PTO rear output shaft below it. The top linkage shown on the Control Box is the spoof control rod linking to the Dump Control Lever. The lower linkage is the control box linkage to the PTO.

 

[BEASTMASTER]

I don't understand . the winch lever has nothing to do with the dump body going up or down. at lest not on my 61 M-51

 

[Robo McDuff]

I don't understand . the winch lever has nothing to do with the dump body going up or down. at lest not on my 61 M-51

Yeah, I found that out this morning as well and mentioned it in the other thread already. My bad.

Which leaves me with the last problem. Same picture as in my post 5 above in this thread.



The Dump Control Lever in the cabin is in upright neutral position. You can see the connector rod between the control box and the rear shifter shaft link on the frame. It is hanging down and the connection to the movable arm on the control box is just visible.

I checked again the different positions of that rod today, with the rear shifter shaft in disengaged position, pointing max backwards.



With the dump control lever in neutral, the rod is sticking about 4,4 cm (0.4 inch) beyond the connector on the frame.
With the dump control lever in hold or up position, the rod is sticking about 5.5 cm (close to 1/2 inch) beyond the connector.

All the rods look like normal, not bent or anything. I am thinking that somehow, during removing or putting back the dump bed with sub frame, the arm on the control box (control box lever?) slipped over the axle sticking out of the box. However, that should not be possible because according the TMs, this is not a splinted connection but one with a woodruff key.

This linkage on the control box looks and moves ok. Since I did not touch the rods or anything for adjusting the linkages, and the linkage between control box and dump control lever fits without problem, I am at loss what happened here and how to solve it.

 

[Robo McDuff]

I think I will just re-install the rear output shaft between the PTO and the pump, but leave the link between control box and rear shifter staff out (not connected). Then start the engine, with everything in neutral, and let Soldier B push the the rear shifter shaft into "engage" to ge tthe pump working. Then just shift the dump control lever and see what happens. IF everything works as should, I will shorten the link and connect everything.

If not working properly,

This week 40 years ago.

 

[Robo McDuff]

Dump hoist control box, some better pics. First of all, the control box lever moving the shifter shaft for the PTO is slightly twisted. It is a bit removed from the box, I was already trying to take it off before making the pic.



More important. looking at the pics in the TM and the different pics on the control box shown by Country , it seems that my control box levers have a different position relative to each other than in those other pics.


Above is the control box in the position "all neutral". The lever for the PTO link - on the picture the lower one, not connected - is at the edge of the box bottom, the lever for the dump hoist - connected to the dump hoist lever - is a bit in front of the middle of the box.

Below is the control box levers with the dump hoist lever in completely "dump bed up" position. The PTO lever in engaged position sticks forward about 1/2 inch in front of the box. The hoist lever sticks backwards beyond the box.





Comparing the two positions with all positions I can find in the manuals and the images from Country, my PTO control lever is shifted forward at least 1/2 inch. The normal position for the PTO lever in fully engaged seems to be at just before the edge of the box, even further backwards behind the box than my "free" position.

Also. when I move the dump hoist lever in the cabin from neutral to its first position, the PTO control lever goes forward about 1/2 inch. Continue moving the hoist lever in position "hold" and "up", the PTO lever does not move anymore, but is completely free; once the hoist lever is in max "dump bed up" position, I can move the PTO lever on the control box forward and backward (but probably not in the disengage position).

Any idea how this lever could have shifted?

A quick and dirty test would be to just make a temp fitting connection between PTO control lever on the box and the rear shifter shaft and see what happens if with running engine I move the dump hoist lever. However, not sure if that would not brake something beyond repair, or, even worse, let me loose all control with the dump bed halfway up.

Alternative is removing the control box and opening it, but I am not happy about that either.

A third test idea we had is to leave the PTO lever on the box disconnected and attached a new lever to the rear shifter shaft so we can engage the rear PTO shaft to the pump directly. You would move this lever from outside the cab, well away from the dump bed. One engaged, we would move the dump hoist lever in the cab. The only thing would be that the pump would get engaged with the hoist lever still in neutral, but I don not see that as a problem. This could solve my control box problem until I can and afford a replacement control box if necessary.

Any quick ideas, is something out of alignment or broken inside the box?

 

[Robo McDuff]

Anyway, shortened the rod linking the control box and the rear transfer shifter, and tried to straighten out the PTO lever on the box. Almost there and then this



The lever broke!!

On the right, a bit hard to see, you see that on top there is fresh brake marks, but most of the break surface is darker, I would say pointing at an existing older crack surface.

Anyway, that's when I had enough. So started the truck, used a piece of wood to keep the clutch down, and used my new "engage lever" to engage the pump.



After 10 years of inactivity, everything still works as should be. Up, hold, down.



I had the bed raised to max, also to get the spare tire and the fifth wheel from the front of the bed to the rear, so my son can take them out with the forklift. I put the bed in half raised position on "hold" and kept it there for 5 minutes to check for slow loss of pressure. Nothing, stayed rock solid in that position.

Rather than trying to fabricate a lever, I think I will install an air-switch to push the PTO in engage, with neutral being without air, and put a strong spring behind it, so without air the lever automatically goes to disengage.