Leveling revisited for MCI 102

[buswarrior]

Keep documenting the build.

The silent viewers will thank you, if they ever meet you in person out there somewhere.

Happy coaching!
Buswarrior

[richard5933]

I'm enjoying reading about it. Makes no difference if I'm going to do the same on my current bus, I'm learning from your efforts and enjoying the play-by-play.

[Jim Blackwood]

OK then as long as someone is benefiting from it. Not much to do today as I'm waiting on orders to come in. My next step is to make a sleeve to mate the front gearbox to the jack. I ordered some 1-1/2 x 1" round tube and I will need to cut keyways in it. The outer one is no challenge, I'll just clamp it in the mill but the inner one? Well I don't have any keyway broaches so that one takes some creativity.

The tube wall is 1/4" and the key is 3/16" I think. Half that in the sleeve. So what I'm going to do is to slot the tube, position the key in place, and then make some heavy tack welds on top of the key from the outside. That will lock it in place and restore the integrity of the tube. Clean up the welds so it'll slide into the reducer, and job done. It won't be possible then to replace the key but that should never be necessary anyway. A snap ring goes in the bore of the reducer so the sleeve can't escape and it's a slip fit assembly. The bracket to restrain rotary motion is all that's required to mount it.

Now overall length may be an issue once a 2 hp motor is attached and probably will be. This gearmotor is really serious overkill. But I can resolve that by swinging the motor end up to the top of the bay and anchoring it up there, more or less parallel to the floor which will also leave more generally usable space below. Photos to follow at some point.

Jim

[Jim Blackwood]

The photo below shows the results of yesterdays labors. In the second photo you can see my method of attaching the key for the inner bore. Not pretty but plenty strong and won't be visible. This piece allows me to hang the gearmotor off the shaft of the front jack, which is today's objective along with measuring amperage draw to determine the horsepower requirement.

Jim

[Jim Blackwood]

Good progress today. Photo 1 below shows the gearmotor attached to the front jack. Pay no attention to the ratchet strap. This is not the ratchet strap you are looking for.
No actually I haven't decided if the motor will hang or be supported horizontally. The good news is that during the test run the motor drew less than 1 amp at any time and never sounded like it was under any significant load. (ain't 3 phase great) So I ordered a hopefully more sensitive amp clamp and will test again later. Since the full rated draw at 220v is 2 amps it's just possible that a 3450 rpm 1/2 hp motor will run it. But I'll wait for the new meter. My old one really isn't sensitive enough to say for sure.

2nd photo shows one of the rear jacks. I really didn't expect to get the drive mounted today but there you see it and I believe it will work well. I will likely add a strap tomorrow to prevent twist just as a precaution but it is ready to test. The other one is waiting on a sprocket to arrive but I may go ahead and mount the gearbox. I also need to come up with a motor for that one but I think I may be able to adapt a C face end bell off one onto another to get something that will bolt up and work. More fun tomorrow.

Jim

[chessie4905]

Pretty impressive. How much total do the three weigh?

[Jim Blackwood]

Oh they aren't light. I haven't weighed anything yet but probably about 50lbs each, plus the weight of the jacks, plus the weight of the trusses. I figure the net is in the neighborhood of 300 to 400 lbs, maybe a bit more. I'll agree I should be weighing what I install, but it won't make any difference I'm going to install it anyway. And the gross gives me quite a lot of leeway so I'm just not going to worry about it too much.

If I was though, I'd go the garage door opener route. Jost are one of the lightest weight landing gear already but they are also made in aluminum, at about 27 lbs each. So that, along with the garage door opener would drop the weight down into the 150-200 lbs range if the side jacks were mounted inboard. I think.

Jim

[windtrader]

I admire your conviction on putting levelers on as it is a pretty big project, time, materials, and $$. Just have to ask, is it really that important to you to have this sort of configuration? I've used a set of drive on ramps when I can't get a flat enough place to park. Works for me and a whole lot less complicated and costly. The ramps do consume bay space but not enough to be of any concern.

[Jim Blackwood]

Don you are right that would be much simpler. But once you have onboard leveling jacks you never really forget how nice it is. I took a hard look at using the airbags for leveling, even spent a few bucks on it. But, on my last RV which was a 32 ft Coachman I outfitted it with a hydraulic system using surplus parts and spending probably around $400-500 doing it. And that worked really well for the cost plus it was very handy to have onboard jacks. But it wasn't long before the cylinders began to leak down overnight and it had to be leveled twice a day. I could see the airbag system was going to go the same way. Believe me, I didn't want to spend 2 grand on the system, and there are other things I could spend the money on, but in the end it is something I will use every time I drive the thing, and in between it will stay put. Both fairly important considerations to me. Like I mentioned I could have kept the cost right around $1000 with just the jacks and cranked them down manually. I might even have found them used for half price, and that would be well worth it. But leveling at the touch of a switch on a cold wet dark night from inside the coach after a long hard day? How do you really put a price on that?

Another thing is that getting the coach perfectly level with blocks takes quite a bit of skill and practice and I won't have the chance to develop that skill before I need it dead level in order to build out the interior and run the plumbing. Especially important since I hope to do an almost totally gravity draining system. With these jacks it's something that anyone could do easily with no real training.

So I'll spend 4 times what my hydraulic system cost. In return I will have a far superior system that can handle many times the weight and is much more stable. I've decided I can live with that. Plus if I need to get under the bus or change a tire it's only a very minor inconvenience to lift it up on the jacks and there's absolutely no need to carry around those 20 ton bottle jacks and jack stands. I think that's how I justify it Don, Just a matter of priorities. And it's one of those things that has to be done first or not at all.

Jim

[Jim Blackwood]

So today I tested the passenger side jack and it works quite well, though it is louder than the front one. Possibly because of the brake on the motor. Didn't need that but left it on anyway. It's a 1 hp 1725 rpm motor. Still really slow but faster than the front one. I can see an auto-leveler in my future.

https://www.bananarobotics.com/shop/Tilt-Sensor-Switch-Module?gclid=Cj0KCQiAhZT9BRDmARIsAN2E-J3d8pJRZmjbV_o7RjE3qqnVUwcCJTCNMvQ_DyAW5QedWRGBJH4KO8waAkgJEALw_wcB

https://www.electronicproducts.com/tilt-switches-a-new-angle/#

https://www.walmart.com/ip/Angle-Sensor-Module-SW-520D-Golden-Ball-Switch-Tilt-Sensor-Module/885745009?wmlspartner=wlpa&selectedSellerId=571

I believe one of these sensors could be tied to the VFD ON command terminal. Seems like a cheap and easy solution.

So anyway, using my old standby amp clamp it looks like this motor was drawing maybe 2-1/2 amps under load and has a 3 amp FLA rating. So well within limits. That was with the rear wheels off the ground.  I'll test again once I have the new meter. One thing throws these numbers off a bit, I am using a 15 hp idler motor to generate my third phase here at the shop so the phase angles aren't optimal and 2 legs read higher than the 3rd one. With a VFD the amperage readings should be lower. My total power usage for this motor based on my readings today would be about 1200 watts.

Anyway I made up the extra brace and installed it. Also cobbled together a motor for the other side. It turned out that the end bells were interchangeable so I just swapped them and with a little cleanup it all bolted together. Great, no more expense there. The sprocket came in and it had no keyway and no setscrew but I did find a suitable 5/16" diameter roll pin so I drilled straight through and pinned the sprocket to the shaft. (Using my hand drill. Try that one on for size sometime on a 1-1/4" shaft.) Swapped the mounting plate position and the vent plug location and set it into place atop 5 two-by blocks and marked for the slots. On this side I had to cut off the shaft on the jack so the sprockets could be lined up close to the jack.

Next I get to lay out and cut the slots in the diagonal body strut which allow the chain to be adjusted, and that's a tricky job, but I'm cutting the slots parallel to the struts so as not to overly weaken them and the nut plate is a 3/8" x 1-1/2" stainless strap that ties both mounting bolts together, adding some strength back in. (had some stock left over from another job) Shouldn't ever cause a problem.

I think I'm going to need limit switches.

So next I get to cut those slots. Oh joy. Well I've been goofing off long enough, back to work.

Jim

[Jim Blackwood]

Two steps forward and one step back. I broke a shear pin and now I have to pull the top off the last jack to replace it. Well, these things happen. Luckily I gained some useful knowledge in the process. First, I now know that when the jack reaches a stop the motor isn't going to slow down. Well that's both a boon and a bust with 3 phase. OTOH the current rise is rather dramatic, something on the order of at least 8X before the pin gave up, and that should make it possible to use current limiting in the VFD to stop the drive when the jack reaches the end in either direction. Testing will tell how well it works to restart it the other way, but in a worst case I might be able to override the current limit.

(A quick and dirty estimate shows a torque approaching 2500 ft/lbs being applied to the 1" shaft of the landing gear and a pull of almost 6000 lbs being applied to the chain at the point of failure.)

So that part is good. And I've now tested all the mechanical bits successfully. And the jacks have adequate travel to lift all wheels off the ground which is how it is sitting now. I'll put a jack stand under it before I pull the cap off that jack that needs to be serviced just in case, since my fingers will be in the gears. And add a link to the sprocket chain, and add the side brace.

Then I think I'm going to take a break from this part of the build and level up the bus nice and accurately. Probably is no more reason to address this thread until I start working on a purge for the rear airbags, and the electrical drive and controls might be better located in a new thread.

However I do feel like the air purge belongs here especially since that's what this thread started off with, and the plan is to purge and drop both ends to the bump stops on arrival at a site, and then use the electric jacks to level the coach. Most times only 2 jacks will be required to achieve level.

Jim

[Jim Blackwood]

Here is the next episode:
https://www.busconversionmagazine.com/forum/index.php?topic=35152.new#new

The build thread is here:
https://www.busconversionmagazine.com/forum/index.php?topic=34360.30

Jim

[windtrader]

Jim,
This story has been going on nearly as long as COVID-19 with about the same progress toward the finish line.  You get mucho kudos for your passion for this feature, obviously high on your wish list.
In the beginning, functional specifications weren't mentioned; specifically, how much range are you building in?

Why does the typical solution of valving the existing air bags not satisfactory?
Did you consider an auxiliary air bag system?

I know you well enough you will have a workable leveling system but personally it seems like a lot of energy going into this single feature.

[Jim Blackwood]

Yes Don, you are right to ask those questions. But first bear in mind that I am on the 5 year build plan and some things just take time to get them right. So why not air? Primarily because air suffers from the same problem as hydraulics, in that they have a tendency towards leakage. This is easily overcome in a running system but in a static one not so much, and from experience I can tell you that it isn't so much fun waking up with your head downhill and then leveling the RV twice a day. There is a rumor going around that an air system can be leak free but that's never been my experience and I'm not basing my future happiness on my skills at relentlessly chasing that elusive goal. Plus the mechanical system is more reliable/safer as a maintenance jacking system. No concerns about getting under the bus in other words, as it isn't moving.

As features go, I'd say it is as important as say, a solar collector array, and about 1/4 the cost, maybe less. So as a personal preference it isn't that hard to justify. As for the work, well I happen to be very skilled in those arts so that wasn't any great challenge. I simply threw together a workable solution from available parts. And that is also why I didn't start with the specifications, as those were going to change and evolve during the build process. Consider for instance the final gearmotor choices vs the initially quoted motorized Chinese screw jacks. Either would have worked but these cost less, were more easily available, are weather protected, mounted more easily and take less power to drive. I believe the full travel distance is 13-3/4", and the feet do protrude slightly when fully retracted but not enough to scrape on speed bumps. Even Florida State Park speedbumps. That's enough travel to lift the wheels off the ground. Even more height can be gained with blocks and I believe a 6x6 will fit.

BTW, I did consider using the airbages for leveling. In fact I bought valves and such to do it and had modified the front kneel controls to allow that. I was ready to look at the rear as soon as I had the bus on jackstands. But you know, a curious thing happened. I realized that onboard jacks would be better than jackstands and matters just evolved. Now, I will be using the air controls for leveling, and in the following way: Upon arrival I will purge the air bags to drop the coach down to the bump stops. Then use the air to level it up roughly, and then switch on the automatic leveling system which I haven't designed yet. That is the final phase of the mini-project, coming up with some sort of a controller that can extend the jacks, level the coach, and shut off. I have plenty of time to develop that part as it is the least essential part of the system.

Jim

[Jcparmley]

Jim, keep up the good work.  I am very interested in how everything turns out.

Jared

Are you guys still interested in this? If you aren't that's OK, just one less thing for me to do. I do realize it's drifting into the more arcane part of things what with gear ratios and current draw and whatnot. Sometimes it breaks my brain to think about it.
But anyway, yesterday I ordered sprockets for the two side jacks. I was fortunate enough to find what I needed on ebay and was able to get all four for around a hundred bucks so that was a pretty good deal. The chain I have enough of. It's motorcycle chain so I may have to thin the teeth a little but that's easy to do. It's 40 pitch which has a 1/2" spacing between the pins. For this application I think it'll be fine although nominally it might look a little on the skimpy side. It has to handle about a 750 lb pull and I think the rating is about 525 lbs. I found two 60 tooth sprockets with a 1" hub and those will fit the available space. For the reducers I found one 13 tooth 1-1/4" bore sprocket  for the 60:1 reducer and a 17 tooth 1-1/2" bore sprocket for the 80:1 reducer. That should put me close to 280:1  on both sides. The front is 541:1 with a 1725 rpm motor so if I switch to a 3450 rpm motor it will double the speed. That is roughly equivalent to cutting the ratio in half which would be 270:1, meaning that the front and side jacks will then be running at the same speed.

The question then becomes the horsepower requirement which based on earlier testing should be no more than 2 hp per motor and the next test using 3 phase power will nail that down more closely.

Now then, 3 phase power on a bus you ask? Yes well, things have gotten more inexpensive you see. Today you can buy a VFD drive that will run on 220vac for about $65 and power a 2 hp (1.5kw) 3 phase motor so it's reached the point of affordability. And that drive is easily reversed with an external switch and also has some pretty sophisticated electronic controls. Like soft start which we find useful. It may even be able to run the motor at a higher speed under no load conditions. So a simple up/down switch on the console ought to do the trick. It also lends itself well to an automatic leveler that can be added later.

To power that VFD (and at the 1/2 hp level they can run on 110vac which can be very useful sometimes) all that is needed is a 2kw inverter. You can buy those with a sine wave output all day long for about $35 each, meaning the jacks can run on battery power if needed. Or the generator, or the shore line. That takes care of that.

The motors may be a bit expensive but there are quite a few available for under $100 so hopefully I can find the right combination of rating, shaft size, speed, voltage, mount type, and size in that price range. If not, the cost of new is not prohibitive. Even so I think I still have a pretty good chance of keeping my total cost under $2000 which is exceptional for such a robust leveling system.

Jim