HK Trucking

Electrical on that yellow stuff sure can be a PITA!!!!! We have a lot of trouble with wiring harnesses where they flex at the articulation point on the front end loaders. Things on the front half of the machine quit working, and 9 times out of 10, that's where the problem is!

That's what I'd do if it was mine. Don't forget to pressure test all the welds with soapy water, and re do any pinholes before re installing the tank.

I hope he doesn't encounter a jammed adjusting ring with the old "lockstrap" type adjuster!!!!!! Time to get out the air chisel with a long blunt bit, or long steel drift & 5 lb. hammer!

Using a "test light", clamp the test light cround clamp to the truck frame (clean the paint & rust off where the clamp is placed to insure a good connection). Touch the test light probe to the positive bat. cable connection, if the light comes on, then your system is negative ground. If the light comes on when you touch the test light probe to the neg. bat. cable connection, then your system is positive ground. No batteries in it? Then as Rob said, you can tell which cable was positive because the terminal hole is larger, and the negative cable has a smaller terminal hole.

Use it for oiling the bar & chain on your chain saw. .

Amen to that!!!!!!!!!!

Well, that would be enough for your lunch Rob, then you'll have find something else for supper!!! .

My calculations were based on 11R22.5. .

That's incorrect. On initial fill, you fill the upper & lower compartments (and the power divider on the front diff), thereafter for routine maintenance you just check the bottom compartment and keep it full to the filler hole. If you keep checking & adding oil to the upper compartment each time, it will result in the bottom compartment becoming overfull, and you'll be draining the excess out each time, which makes absolutely no sense, unless you like wasting gear lube.

64 MPH @ 1500 RPM. 90 MPH @ 2100 RPM.

I remember that very well. Guess that means I'm getting old!!!!!!!! Funny thing is, in those days, without the "help" of computers, it seemed like I always got the right part, and it was usually in stock. None of this "we'll have it for you tomorrow" B.S. .

It'll fit, you'll have to shorten the driveshaft because the back box on a quadruplex is a lot longer than the duplex. Also, make sure what type of clutch is in your truck. In a B model it will have either a push type single disc clutch, or a push type double disc clutch, you have to find a quad box with the correct bellhousing, input shaft etc to work with the type of clutch you have. Regarding the trans from Joe's Mack, I'm not sure what year his DM600 is, but unless it's a very early one, the DM's usually had the pull type double disc clutch setup. You could possibly mix & match parts from the front of your Duplex main box to make it work if it's set up for a different type of clutch than yours, or change your clutch & flywheel to match, but if you go from single to double disc you'll have to redrill the frame to move the trans mounts about an inch, and also if you go to a pull type clutch in your B model, you'll have to re engineer the clutch linkage to pull instead of push on the throwout bearing. Edit: I see Joe's Mack DM is a 1969, so that would almost certainly have the pull type double disc clutch.

Sounds like a shitty job!

What size rubber is that truck on? When I was back east we had 7:00 rears behind a double over quad box, on 11:00 - 22 rubber and they would run 60 MPH @ 2100 RPM. Is your engine achieving 2100 RPM? If not, fix the throttle linkage or adjust the hi speed stop screw so that it does get 2100. .

Yeah, had to think about that for a while, it was Nick Domain that owned Domain Sand & Gravel, then his son in law Ray DeMers kinda took over in the 80's. Ray was always at the pit they had in Dover. Domain's motto was "Where Bulldozing Is Not A Sideline". They had that printed on all their tickets. .

Domain Sand & Gravel?

At the time of manufacture, Mack specified 85w-90 mineral based gear lube for those transmissions. I see no reason to use anything different now. Another hint to help your transmission: don't try to engage reverse while the truck is rolling, or with the main stick already in gear. Shift into reverse with the truck completely stopped and the main stick in neutral, then once the compound is in reverse, put the main in gear. Those transmissions had a habit of breaking a tooth off the reverse idler gears if shifted into reverse roughly. .

David, go to the Velvac site: http://www.velvac.com/pdf/air.pdf Scroll down to page 59, and find part # 320131, that's the valves we use. Probably not a good idea to run all that water & air tank sludge through it though. I hear ya on the 2 wheel morons!!!!

The right way would be to build a new tailgate of the proper dimensions. Temporarily you could get some 1/2" 0r 5/8" square stock and with the gate in the latched position, weld it to the sides of the gate so it is tight against rhe dump body opening. If the square stock interferes with those spreader chain hooks you may have to trim the pieces at the point of interference just enough to give clearance. Unless you only haul "fine" materials like sand & topsoil, forget the rubber gaskets, they wouldn't last a fartin' spell! Do get it fixed up though, that's just a broken windshield insurance claim, or D.O.T. spillage citation waiting to happen! .

If the blower does not work on the hi speed setting, then there's something else wrong. The resistor is not part of the circuit when the switch is in the high speed position, so therefore the problem could be in the switch, motor, wiring, circuit breaker, or it could be a bad ground.

That's how I do it too Glenn, on the new ones I set up where I work. We use the electric over air solenoid valves connected to switches in the control console in the cab. Switch on = release pressure on the up bags,pressure on the down bags. Switch off = release pressure on the down bags, put pressure on the up bags. That way the default setting in case of an electrical failure is "axle up". Regulator & gauge on the down pressure port of the solenoid valve to adjust axle weight, full system pressure to up bags to prevent axle bounce when raised. QR valves on the frame just above the lift axle(s)to exhaust the pressure fast. I've also seen some that use relay valves mounted near the axle to fill the bags more quickly.

Just run the blower on "hi" all the time, no resistor needed.

Seems kinda like a contradiction. Why would they want that long nose out in front, when the rear is chopped as short as possible to maneuver into tight jobsites with mobile homes? I like Superliners, but I don't think that is the right truck for that application! .

Replace the regulator too, if you haven't already. A few years ago I had a regulator go bad, it would work properly when the pressure was on (down) but would not let the air come back through when the push pull valve was moved to the up position, therefore the pressure was still held against the QR valve & bags even when the control was in the up position.

I've also seen it happen, and the results aren't pretty! With the old serviceable type ends it's usually caused by the spring breaking between the adjusting screw and the cup that rides on the ball stud. That allows the cup to back away from the ball and the link can come off the ball. A 1988 would have the non serviceable drag link, and as Rob said, the main cause of failure on those is lack of lubrication over time, which causes extreme wear of the joints, allowing the joints to get so loose that the link eventually can pop off the ball stud(s). I'll never understand the mentality that leads to lack of lubrication on critical parts. Grease is cheaper than parts and it is much easier to install. .