We have this old Mack MD800 that still runs but we have doubts on how to control the dump on it and where’s (If there is) a parking break on this truck as it runs as if it were stuck (might also be lack of use) i put a picture of the controls but don’t know what is what, anyone know this truck?
Not sure where to start on that mess. Looks like that truck has led a very bad life. A dump truck with a fifth wheel control valve? Would not want to guess that anything is as it left the factory. Is there a brake drum on the driveshaft at back of the transmission? Maybe post a couple pictures of the area behind the rear wheels. But seriously you need to find someone who knows about trucks to look it over before even thinking about moving it or someone could get killed!
I would guess that one lever puts the pto in gear. Pull one with it running and listen for gears grinding. The other would be the up and down. Must have been a tractor. Park brake might be the button with the wire wrapped around it and the knob is missing. Try going under and seeing what linkages or cable are attached to the PTO and pump. I would guess something that old will have a driveshaft running from the PTO to the pump. That cable might do it. It must have air brakes as it has a spike on the steering .
Try this https://www.bigmacktrucks.com/
This thing has been butchered terribly, it's very difficult to determine what's what from the pictures. Those two lever's in the floor should control the dump, one would go to the PTO and the other to the hydraulic valve. Best thing to do is crawl under the truck and have someone work the levers and see what they are attached to. I suspect that shaft with no knob on it on the back wall bracket and leather string dangling from it may be the parking brake, those look like they could be air lines going to it. Again, tracing them out will tell you for sure. Mack is a damn good truck but it looks like this thing has been cobbed up each time it needed a repair and will need some sorting out.
Agree! Seems like every owner since 1969 added something to that truck and never removed what the last person had installed! Needs someone to tear into it and strip out all the un-need junk to get back to basics. Where I worked had many DM800 dumps for off-road stocking trucks and they took all kinds of abuse with relatively little problems.
He's got that right. I ran a brand new 1990 R model tandem dump with a set back front axle, 350 Mack with an 8LL, Mack rears. We hauled along side of wiggle wagons for 3 years. Loaded heavy all the time, and wallowing in mud. Never any issues