Geoff Weeks

Ok, I'll preface this by the fact I don't know your year, but most all bunk units I see have a solenoid valve that cuts the refrigerant when the bunk system is not turned on. That would be the 1st thing I'd check. should be powered when A/C is called for my the bunk control. Bunk units I am familiar with have their own Tx valve, so that is number 2 Next look at the unit itself and see if any refrigerant is flowing in the bunk unit. Look for temp change on the liquid line before and after the Tx valve. If none, then there is no flow (likely number 1) if there is a temp drop but the outlet tube is warm, it may be low on refrigerant and the front is 'hogging" all the liquid.

Heat was there when just the bearings were "hand packed" with no "extra" grease in the housing, so that isn't the cause in this case.

Terms can get confusing esp when "slang" and regional differences come into play. To be clear, I am taking about a driveshaft mid ship bearing and not anything contained in the rear axle housing. Yes the left and right bearing inside the axle housing are also called "carrier" bearings, because they support the (carry as it were) the differential, which is housed inside the carrier itself. Clear as mud, and the more I try and spell it out the more it will confuse things! Most longer wheel base trucks today have multiple shafts sections with the back end of each supported by a driveshaft carrier bearing, often suspended from above. Unlike the modern practice of hanging the bearing from two bolts, this one passes through the crossmember and is held in with a ring of 6 bolts This truck has the carrier or "midship" bearing where the shaft passes through the frame crossmember. The bearing must "float" on the shaft to allow for minor fore and aft as well as concentric adjustments of the whole housing The double taper roller is supposed to have .005 to .008 of "slop" in the bearing assembly, so no pre load in this application. It runs in grease, and that may come into play as well. Bearings run in an oil bath can remove the heat, those in grease can not. (or not as easily). To adjust the bearing, you select the spacer ring that provides the desired fit. Too tight and you risk the whole bearing spinning in the housing, too loose and you will introduce run-out and therefor vibration into the shaft. The problem I was having was, after running the shaft at max speed for just a few minutes the bearing housing was getting so warm you wouldn't want to keep your flesh on it for more than a few seconds. It may be normal, or it may not, I have little to compare it to other than wheel bearings, which turn slower but don't generate anywhere near that amount of heat after hours of running.

Pinion bearings are a good example of bearings that run "back to back with a preload and high (relatively) high speed. In the case of the carrier bearing, they are factory (bearing mfg, not truck mfg) set and sold that way. I don't know if over the years, the roller races have been changed, they're not supposed to be, the bearing gets changed as a unit. It is made up with "off the shelf" cone and a double cup outer race, but the spacer is selective fit.

I can think of plenty that run with pre-load. Spec for this bearing is .005-.008 measured at the outer race. Just feeling by hand, I think it is tighter than that.

On mine, the dual rear windows in the cab slide down, something I had not seen on any other truck. Spring loaded up with a friction lock to hold open. Can't believe the condition of the cab for a truck of this type. few if any dents and almost no rust. The frame is another story, ,any welds and changes. Anyone wanting to make it into a driveable truck would be best to mount the sheetmetal on a newer frame.

Still haven't checked the carrier bearing. When I was diagnosing, I dropped the rear shaft and ran the engine and trans in top gear at rated speed and noticed the bearing housing got warm enough you couldn't hold it for more than a few seconds. I figure 125-135 deg F. It got this hot in a very short time of running at speed. This truck uses a double taper roller with a spacer supplied by the bearing Mfg. I ended up replacing the bearing (s) although they looked ok. I'm not sure if it was on the tight side or not. I saved the old bearing and put a N.O.S. bearing in. I need to put the bearing in a press of vice and see if it has pre-load or any play. I think I might mic the present spacer for the old bearing and order one a few thousandths thicker. It doesn't use the more common type of ball bearing in a rubber mount. It has a tubular housing that holds the double bearing and the housing is mounted in a "clamshell" mount with a rubber ring between the housing and clamshell.

I guess shafts with cross and bearing type joints set up a standing wave at one RPM (critical speed). The size of the shaft and the length determine when that happens. To avoid it, you can make the shaft bigger or shorten each section.. Also they found that at exactly 1/2 the critical speed you can also get a vibration so while you can pass through that speed, you don't want to run at that speed for very long.

Well it depends, The smallest ones were "legal" highway sized Kinda like some KW's they could be bigger and wider. I hauled a KW that was 11' wide. Mine is 8' wide.

One more

You shamed me into crawling back there.

It was hard to find, on the north side of the RR tracks, you had to snake through a neighborhood, and by an old elevator. Only reason I knew about is a guy on a train crew, took pictures and did a little research. One time when I was passing through I dropped my trailer and went bobtailing around trying to find it. All I had to go on were the photo's. There were old stock trailers, a Cabover Mack (in sad shape) and a bunch of odds and ends. I got there when I heard they were going to be cleared out. The train guy knew about it because he was going to have spot some gondola cars. This was back in the early 2000's.

I saw S&S had kits, then noticed the date on the .pdf (2016)! My 1989 had one from the factory, a little while later they came with either TRW or M-100 box, so I am guessing they went out of production around 1990. I was at the RH Sheppard factory sometime in the 90's, all I saw was wall to wall gear boxes.

It came from Dan Wither's fathers closed yard Closed in the early 60's I guess by what it held. The Withers own SW truck parts. From what little I know about mine, it was a oil field rig truck (both the model and the use) that was used in Ok and Ks oil patch. Someone cut the big winch off the back (not removed, but cut!!) most everything in the closed yard had the rear ends missing, mine included. Also the 3 spd aux with power-tower was gone. I've got a 4 spd aux for the truck. I never should have got it, too big a project for me. There was a beautiful Diamond T truck I should have bought Still had the leather corner "pads" on the butterfly hood. (rears missing) but looked like it could have been driven out except for the missing rears. The yard was closed in the early 60's and just sat until Pratt made them clear it, sadly I suspect most went into rail cars, and scrap.

Ah, yes I know where that is. There is or was another (Dart) at Russell, Ks. Mine came out of Pratt, KS.

Oh boy, My guess is if they no longer deal in them, that the parts supply has dried up. I think the place mine was sent to for rebuild was: https://www.pss1.com/ If they tell you the same, I would guess time has run out on them. I don't remember when I had mine done, it might have been 7 years ago or more. I just don't remember. Might contact RH Sheppard direct and see what they say. https://www.rhsheppard.com/products-services/products/remanufactured-parts/

Where did you see the one posted here?

I have a Dart a few years older that that one ( I think) Mine has one piece side windows and more "trapezoidal" windshields, but the telling thing is DART is in script on the radiator. Mine is a "project" that never got started, and will never get done (by me). When I get the barn cleared to the back where it sits (inside) I'll get some pictures and post them (don't hold your breath).

Your's had the two set screws? The one in the weeds I posted does also (you'll notice the arm is still on that one!) The one the cabover took had the big Allen head bolt in the center. I had a hardend 3/4" drive socket to get it out. Look for punch marks (or make them) to be sure to get it back on in the same orientation, although some will only fit in one place. I used a big bearing splitter behind the arm and a puller to pull it off as I didn't have a gear puller of the correct size. I think getting the set screws to come out after all these years would be the worse part of the job.

It was the last time I needed them. They were in use at least through the end of the 80's. It is the two digit boxes that parts are no longer available. If in doubt call Straight Line and ask if they will have a problem.

The British and Austrian buses we got didn't have driers and use the discharge line unloader, so will not work with many (almost all) North American driers. With you guys getting so many Pommy and Europiean stuff, that may play into why driers are not as common for you. The AD-4's I put on my stuff worked real well, Nothing out the wet tank, nothing out the trailer tanks. If I saw even a little moisture in the wet tank, I knew something was up. I had two trucks with AD-9's and they did ok, but when I saw moisture I knew there was a problem. Problem turned out to be the threads holding the element in the drier. That is when the AD-9's got swapped for AD-4's. I could pick-up core AD-4's for about $20, kit em and be good to go. I never did yearly services, I just kept watch on the wet tank, and when it started to show moisture, it was time for some action. I had air start, so moved a fair bit of air though the driers over the years. On the other hand, my trucks air systems were kept tight, so running down the road, there was little air put through the drier.

Forgot to check the carrier bearing temp, didn't want to crawl back under in the wet. I'll check next time it is out.

Ran to Omaha, and picked up the shaft. Rain stopped enough for a while for me to put it in. Took it 12 miles and back to put 20 gal of gas in the new tank. I think we have a winner. I can run up to gov speed in O/D and while not silky smooth it isn't trying to tear itself apart. 55-60 is good enough. Speedo doesn't work correctly at present but I was keeping up with traffic, Tach wasn't at gov speed, so likely 55 -58 without problems. Old and new shaft. Old has the old diff and carrier bearing yokes on the ends, so that is why it looks floppy. New shaft is 3 1/3" old is 2 1/2". The bigger shaft looks none to big on a truck of this size.

Wow, sorry to hear that Jim. Hope you have a speedy recovery. I'm finding age makes a fool of my mind. Mind tells me I'm still 26, body says nope, not really! Glad to hear your back, may be time to sit inside for a while and spend some time on the boards, and out of the shop.

Called this Am, the new shaft is finely ready for pick-up this afternoon. I will get it tomorrow and report back on how it works out. They said they had a delay in getting the slip-spline or slip yoke ( I don't remember which) and that is why it took so long. Not a problem, as I don't drive the '41 often.