Interesting dump mechanism

[bcp]

I've been looking at the methods used for dump trucks before hydraulics were common. I usually see gear drives or cable and post. This is a new one for me.

This is a large photo so you can zoom in.

From:
GMC Heritage Editions Unveiled | Pro Pickup

1912 GMC

 

[Donman]

That is intriguing! I looked at it quite a while and still don't know if I fully understand it all. It appears that those lift arms where the chains are connected would almost touch the ground by the front wheels when the box is down because those angle iron drops that are riveted to the frame behind the front wheels would prevent the arms from moving parallel to the frame. Or does the connection to the box at the bed have rollers that roll back when the arms hit the angle iron drops?The box pivots down low on the wheel axle and it appears that it has to get started lowering with the chain pulling it down until gravity takes over. Thanks for posting!
Donman

 

[bcp]

There must be just enough clearance to get by. That's the only place for them to go.

I think the angle iron keeps the lift arms away from the spring shackles. etc.

Bruce

 

[yankeerider]

Of course the dump body is chain driven. The truck is, too!

 

[Artisan]

The billboard in the rear, says "Les Miserables" yes? Interesting.

That truck is a beaut!

 

[284 International]

I think the arm attached to the bed is hinged and fixed there. The chain pulls on the opposite end of the arm, effectively shortening the base of a triangle, tilting the bed up, kind of like pushing an open, face-down book's edges together would raise the spine. It looks as if the arm is carried on the roller to reduce friction and carries the beam as it rides back and forth. As the chain shortens, the frame member pushes the bed up, and carries the slack chain with it.

Cool find, thanks for the picture!

 

[blunosr]

Wasn't there an army utility trailer with a dump like that? Flip a lever and back up and the bed lifted up as you reversed (or pulled forward would make better sense)? I'm sure I've seen something military that did that.

Bye for now,

Troy

 

[The Haymaker]

That is intriguing! I looked at it quite a while and still don't know if I fully understand it all. It appears that those lift arms where the chains are connected would almost touch the ground by the front wheels when the box is down because those angle iron drops that are riveted to the frame behind the front wheels would prevent the arms from moving parallel to the frame. Or does the connection to the box at the bed have rollers that roll back when the arms hit the angle iron drops?The box pivots down low on the wheel axle and it appears that it has to get started lowering with the chain pulling it down until gravity takes over. Thanks for posting!
Donman

The arms are on a fixed pivot on the bed and guided by the rollers on the bed. As the bed comes down, the arm tips will arc forward and up, probably finishing parallel with the frame.

I love old machinery. It intrigues me what was done before the days of welding, hydraulics, lightweight alloys and everything else we take for granted.

 

[tommu56]

It is the same thing when you get a regular dump with a frozen load and wont come down, put a chain from the bed down and under the rear wheel and pull forward pulling the beed down till load gets back over center.

tom

 

[sparc]

I think the arm attached to the bed is hinged and fixed there. The chain pulls on the opposite end of the arm, effectively shortening the base of a triangle, tilting the bed up, kind of like pushing an open, face-down book's edges together would raise the spine. It looks as if the arm is carried on the roller to reduce friction and carries the beam as it rides back and forth. As the chain shortens, the frame member pushes the bed up, and carries the slack chain with it.

Cool find, thanks for the picture!

In place of the chain drive what if you mounted a winch at the rear of the truck frame ans used it for controlled up/down? If on a trailer you could mount the winch up front and run the cable to the back through a snatch block then back toward the front to grab the arms. If you did it this way the winch would be available for dragging things into the trailer bed by rerouting the cable as needed. I think you can get wireless remotes for winches and that solves the control link problems.

 

[284 International]

In place of the chain drive what if you mounted a winch at the rear of the truck frame ans used it for controlled up/down?

That would work, but you would either need to run a pair of winches, or go to a single, center mounted lift arm.

if the winch were mounted at the front, going around a pulley to the lift arm would double the compression force seen by the bed or truck frame. I think swapping the cable(s) each time would be annoying. Winches dedicated to either or loading exclusively would make more sense to me.

 

[284 International]

After looking a bit, I found an old advertisement that shows the bed party lowered. It is about 3/4 of the way down here, along with some other neat pictures of the Reliance/GMC trucks of the period.

http://www.shiawasseehistory.com/gmc.html

 

[bcp]

That looks more like the winch idea. Instead of a chain, it seems to be a strap that winds up on the powered drum.

Bruce

 

[Ken45101]

Wow! Impressive.

Look at the tires. Can you image what a dump truck on those tires with the roads of that era rode like? Maybe that is where the "rides like a truck" expression came from

Thanks for sharing!

Ken