Geoff Weeks

Not up on the newer stuff, but I know Meritor (Rockwell) made some double reduction units. There are two different capacities you need to consider, one is the housing and brake capacity and the other is the torque/reduction needed to move that. The double reduction were built like a standard front of a tandem with a high input and a bull gear on the pinion, but differed in that the drive ratio wasn't 1:1 from the input to the bullgear on the pinon. housing and brakes were higher capacity, allowing to carry more weight.

The switch allows you to quickly test that both are working, You should see an RPM drop when firing on only one, often around 50 rpm. Start on both, flip to one, then the other, to check and then back to both.

It could be as simple as one module on the bus not "powering up".

Canbus problems and digital stuff in general is not my strong suit. However, there are people with video's on the net that can help. It would seam, and I can be wrong, that something is bring down the bus. I think the way to test is resistance across the high and low canbus lines. If it is off, then start un plugging (disconnecting) modules until the one that is causing the bus to go down is removed. Again, I am very weak on this subject, but with multiple comm errors it seams to point this way. What you don't want to do is start replacing modules trying to hit the right one, that can get very pricey and takes longer than finding the one that is causing the buss errors.

If you are removing the ground, but leaving the + connected, then you will see a voltage between the frame and the - side of the battery. Esp if measuring with a digital voltmeter. The question is: are you seeing a draw on the batteries when everything is shut off?

Paul, I'm embarrassed to admit I learned that one very late in life from someone else, but it does work, at least on the ones I tried it on.

Ken, I wouldn't say it was easy (esp in stainless steel) but is doable by someone who can flare and braze. If you have your old one to use as a pattern, you'll not need a drawing.

What I was looking for, was if there was battery voltage at the output stud. A test light is simple and easy to use for that. I wasn't concerned about regulator settings, as these type are fixed. either it charges to the set voltage or it doesn't. Another quick check you can do with the engine running is hold a small piece of steel close to the rear bearing, (A steel key ring will do) and if it is attracted to the alternator, you know the rotor field is energized. Once you know it is charging but have other problems a voltmeter is handy to have. A test light is quick and visual to see from a distance and almost impossible to mis-read. It will not tell the voltage, although if you "know your light" you can make an educated guess, but for work/doesn't work determinations it is a useful and rugged tool to have in your tool box. I wouldn't carry my Simpson meter with me in the truck, but I can diagnose most simple electrical faults with a testlight.

Here is my repair.

I don't know what the MH one looks like, but for my cabovers I made a new tube from 1/2" stainless tubing. length is the critical dimension to get right. On mine the bottom end was a compression fitting and the top end was a bell mouth to accept the "stopper" end of the dipstick, it was a separate piece from the tube itself, and was brazed on to the tube, I heated, removed from the old tube and brazed to the new. Stainless tube is hard to bend, you could use plain steel tube, which is easier to bend. Trick to bend tubeing: make the tube longer than it needs to be by an inch or more. flare both ends with a flaring tool, after installing(temporary) flare nuts. cap off one end and fill the tube full of "sugar sand" tapping several times to make sure it is well packed, then install the other cap. With the tube packed with sand, ends capped off, bends can be made without kinking it. If you try and make too tight a bend you can still split it, but most bends can be made easily. When bent to fit, cut to length blow and wash any sand residue out of the tube, and braze on the bellmouth!

I'm glad to help/

The type I think is supposed to have is what I have heard termed "vari-rate" spring pack, with a main pack and an aux pack above it, the top leaf on the main has the eye on one end to take the torque load. Very common single rear suspension. edit: may not be the top leaf, but one of the leaves in the main pack has the eye on one end.

Yeah,I saw the spring and thought "what the heck is going on here" but don't know Macks all that well, and don't claim to have seen everything so didn't say anything.

This ad lists a bunch of interchange part numbers which may help in your search: https://kuwait.whizzcart.com/product/19384513/new-diode-trio-compatible-with-1a-leece-neville-79021-33-500-l79027-l79027hd-505202-l79027hd-1-33-500-1-l79027-1-171-16000/ I looked up 79021 and 79027 on my search.

Diode trio and connection marked in black https://www.ebay.com/itm/302551471197

Ok, that is good news, You do have power to the alternator, so a wiring fault between it and the batteries is unlikely. In North America these are referred to as "one wire" type alternators, A bit of misnomer on the L/N because the case isn't the "ground" for the alternator. They "turn on" by residual magnetizem in the rotor producing a small amount of current in the stator, which runs through a separate set of diodes (diode trio) and is fed back into the field (rotor) regulator to turn it on. The regulator also is connected to the main output studs internally so when it turns on can supply battery to the field. The little wire between the two big wires is the feed from the diode trio to the regulator, to tell it to turn on. If your electrical guy doesn't know this, he may have supplied external power to that wire and the regulator turned on and worked. If that is the case the diode trio is the problem. It is the white piece that is connected to the three small studs and has the wire coming out of it to the little ring terminal up by the regulator. That trio is replaceable I am assuming (never a great thing) that he knows how to test the output current and main rectifiers when he did get to to charge on the bench. So assuming that is true it looks like you need a diode trio.

Test light will work fine, for seeing if he has power to the output terminals! There should be power there all the time, even with the engine stopped or the key off.

Spoke hubs are part of the axle/brake combo. They are generally sized by the axle weight rating and the axle shaft design. So a hub on a DS402 the hub must fit the axle housing and the axle flange. The hub bearing size and placement is determined by the axle mfg. I used spoke hubs from a Volvo with a DS 402 on my Marmon with DS and later DT402's

If the light doesn't light across the two big terminals with the engine stopped, then you have a wiring problem. There should be 12 volts across the two big terminals at all times. I can see the - goes right to the block, trace the +

Front brakes were optional on TRACTORS, at one time, I believe straight trucks need front brakes regardless of year. Edit, my bad, I thought this was the firetruck thread.

Yes, I have it. May be a day or two before I get it to the post office. I am knee deep in a few projects.

What I got: some defects in the chrome top (bubbles but still in one piece) IHC part number but looks similar. same deal as the speedo, you pay shipping and it is yours for free.

I have no idea on Mack if it is normal, I was just saying it can be. In any position does the non-rod side not have air? The rod side can have air at all times in some applications, but the non rod side must be vented in one selection at least. The only way the piston will move out is when the rod side has air and the non rod side does not. The rod side has to be at a higher pressure than the non rod side to move the piston away from the trans case.

1st let me state, I have no experience on the Mack transmission in question, however I can answer your 1st question. Yes it can be normal to have pressure to both sides of a piston, Eaton does this on theirs. Because the rod takes up some area on the rod side, that "working" area is smaller than the other side, so when pressure to both, the piston moves to the rod side direction, when the back is vented the piston move the other way.

I drove a IHC firetruck that had that shift pattern, also my parts Fleetstar did also. odd, but not on common. 1stwas really low and not used when on hard pavement.