Last week I had the opportunity to get dirt and I decided to make the most of it. Some of you may recall
last year Megan bought a vintage camper, and towards the end of the season we had some problems raising the top, which caused all sorts of concerns.
For those not familiar with such things (which admittedly was me as well, so no shame there!) the system works pretty easily. You fit a hand crank into the rear gear box and turn it. Attached to the front of the gearbox is a drive shaft that is connected to the front gear box so that it turns in unison.
Inside the gearbox are two contra-rotating gears that turn in opposite directions pushing the links in chains outward. The chains, one at each corner push the top up. Here’s a diagram that probably illustrates it better than I can.
I assumed it was a simple fix, since it’s a fairly simple mechanism, but Megan went dark and eventually got me paranoid that it was an internal catastrophe. You see, many of these units had plastic gears and the concern was that the gear teeth had broken. My research had shown that the teeth in this one were aluminum, so I was a little less concerned, but they also seem to have been sort of random, almost haphazard, in the way they were manufactured, so pretty well anything could happen.
Some potential causes we were told about were some shear pins, designed to bend or break before anything major broke, gear teeth missing or chain links broken. The only parts supplier we know of had run out of gear boxes and parts and didn’t expect to have any before the end of the summer, which meant that if that was the problem, we wouldn’t be able to use it this year.
But, I decided to spend some time looking at the gear boxes and servicing them to see what the problem was, and greasing the gears as they probably needed it anyway.
I started with the front gear box, held in with four bolts, and almost immediately figured out what the issue was- it wasn’t the gear box, it was the drive shaft, as you can see below. Years of use have worn the shaft away so that what used to be a nice U shaped cutout with rigid sides has been stretched out to a round bottom V. This was slipping off the front gearbox which meant it wasn’t turning with the rear gearbox, which meant the rear of the roof was lifting and the front wasn’t, which is exactly the problem we were having.
Still, who knows when the last time the gearboxes were serviced? And, since I had everything laid out to service them I figured it was stupid not to. Here’s the diagram I was working from:
It was simple enough. Once the gearbox was off I inspected the chains (or what little I could see of them) for any obvious signs of damage but couldn't see any. Of course, at almost a meter long, there could have been all manner of issues further up the line, but it's many hours' worth of work to check those out properly, so I didn't bother.
And here you can see how messed up the shaft is:
For comparison, here is what it looks like with the gearbox on:
And here is what the other end of the shaft looks like, connected to the rear gearbox properly:
Needless to say, one doesn't need to be a rocket scientist to figure out where the problem is here!
As to the gearbox itself, I started by marking the components with a sharpie to ensure they went back together in more or less the same place so as not to mess with the timing of the chains.
This would turn out to be a mistake that would bite me in the bottom later on, but I'll get to that in a bit.
Four bolts hold the housing together, and they were no match for my mighty ratchet. Actually, they came of easier than I expected for something that I had assumed hadn't been serviced in a long time, so I was pleasantly surprised.
The first bit out was this plastic ring that is just used to keep the metal parts from grinding on eachother. A bit of WD40 and some wiping cleaned it up quickly and I laid it aside to reveal:
The first cast aluminum gear. Again, some WD40 to cut the grease, followed by a lot of wiping and the gear was cleaned. Once it was out of the way I was able to look at the shear pin, which, once cleaned up looked just as perfect as it did when it came from the factory over 40 years ago.
You can also get an idea of just how much grease was caked into this thing, which meant that the cleaning and wiping was a bit of a challenge, especially getting in and out of all those teeth! Needless to say, I wasn't planning on using that toothbrush again!
At any rate, I just kept taking one piece out at a time, taking pictures as I went and placing them in order on the deck after cleaning to make sure that everything went back together the way it was supposed to.
At least until I got to here:
Can you spot the problem?
Apparently none of those bearings is actually locked into that raceway.
The only thing holding them in in that photo is the viscosity of the grease, and, yup, they fell out at one point.
I cleaned and greased every one individually before seating them back in with fresh bearing grease, and I was super glad that none of them accidentally fell through the cracks in the deck or that would have been the end of that. (we need a :whew: smiley!)
But I wasn't out of the woods yet. While re-assembling everything after applying an ungodly amount of fresh grease I realized that I had done a slightly too good job of cleaning everything off the gears- including the marks I'd made with the Sharpie to line everything up again.
Needless to say, the gears didn't fit in the chains and I had to do some fiddling to get everything to fit back together again, which was a bit of a pain in the arse, but I got it done. I got a bit smarter when I did the rear one, and instead of using a Sharpie I used a screwdriver bit from from the SOG Reactor to scratch the lines into the aluminum, which really only worked slightly better.
In the end it all got done, everything fit back together and I am going to have to figure out how to deal with that central shaft issue. I'll probably just clock it 90 degrees and cut some new notches, or try and rig up some steel wire to hold it together enough to do the job, at least for now.
And all I can really say at the end of it all is to remark on how good it feels to spend a day or two turning wrenches and making things work again.
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