Wish list for new owners: exterior

[RottieMom]

Originally Posted by Bill

Just an idle thought. It seems to me that the hardest part of lifting the shells, at least on my two TMs, is the first 12 inches or so. Once the shell is up that far, the rest of the lift is easy to do by hand. Perhaps there is some way to install an electrically-powered jackscrew, much like a tongue jack. It would assist with the first part of the lift, then stop and let you take over. That has got to be a simpler mechanism than one that continues to operate all the way to the full-open position.

Padgett, you've thought a lot about this. What do you think? Cindy, would a partial lift work for you?

Bill

Bill, next time I open it (which will be soon since I'm planning a trip to Texas right after Thanksgiving), I'll see what the distance is that's difficult. I think it's more than 12 inches. I'm 6ft tall, and I know that where I struggle is when I've stood up straight after starting the lift. I'll have to check and see how far I've actually raised it at that point. And, I'm actually fairly strong, but I'm a bit worried about when I'm not as strong as I am now. I did get a friend to help me recently adjust the bolts on the torsion bars for the front shell. It was the first time they'd been adjusted and I think we ended up adjusting a full turn but it didn't seem to make that much difference to me.

[Larryjb]

Originally Posted by RottieMom

Bill, next time I open it (which will be soon since I'm planning a trip to Texas right after Thanksgiving), I'll see what the distance is that's difficult. I think it's more than 12 inches. I'm 6ft tall, and I know that where I struggle is when I've stood up straight after starting the lift. I'll have to check and see how far I've actually raised it at that point. And, I'm actually fairly strong, but I'm a bit worried about when I'm not as strong as I am now. I did get a friend to help me recently adjust the bolts on the torsion bars for the front shell. It was the first time they'd been adjusted and I think we ended up adjusting a full turn but it didn't seem to make that much difference to me.

My rear shell is quite easy to open. In fact, it takes more effort to lift in the equalizer hitch than it does to lift the shell. My front shell, on the other hand, is much heavier and tends to bound about as I lift it up. My model doesn't even have the roof AC. The torsion bars are maxed out. I assume that if I replaced the front torsion bars, I would be able to adjust it so that it would lift as easily as the rear.

It seems to me that simple physics is making the shells tougher to lift just at the beginning. The lift arm is extended horizontally and has to bear the weight of the shell is multiplied the most onto the torsion bar. Conversely, the torsion bar is providing the most assistance at this point. This has given me an idea, though. If a thicker torsion bar were used, it would provide a nice lift at the beginning of the lift, but provide too much tension on the shell in the upright position and want to continue to push the shell out to the front (or rear for the rear shell).

Some coil springs are designed with a variable rate spring constants by varying the number of coils, and possibly the thickness of the coil itself. I'm sure it would be possible to make a torsion bar with a variable spring rate to provide even more lift near the beginning of the lift.

What might be more necessary is a latch down mechanism that is easier to use. At least one member uses a lever on the stirrup to give some mechanical assistance to latch the shell. I think it would be easy to weld a bracket onto the frame that could provide a convenient leverage point for a pipe lever.

Maybe be a pipe dream, but at least I'm dreaming.

[Bill]

Remember that with most any spring-type mechanism (coil spring, torsion bar, etc), if it makes the shell easier to open, it will also make it harder to close, since it must re-compress the spring in preparation for the next opening. This can be self-defeating. If the shell gets too hard to close, you have to back off on the torsion bar adjustment, which moves you back toward where you started.

What is needed is an asymmetrical lift aid - it helps as you open, but does not hinder as you close. That was the idea behind my suggestion for the electric motor-driven jackscrew - you can retract it electrically once the shell is open, and it has no effect on closing.

Larry, your idea of the latch-down lever is another good example of an unsymmetrical aid.

Bill

[oldstick]

I could use some sort of handle to grab for standing on the stirrup for the streetside, rear shell. I always do that one first and the first one always seems the hardest. I usually have to awkardly jump up on it with both feet leaving the ground and grab for the roof top at the same time, to keep from falling backwards. The rest are then easy, with the awning available for a hand hold on the curb side.

[Bill]

Oldstick -

I agree that a handle as you describe it would be handy. But let me caution against using the awning as a pull-down handle. The awning has been known (on this forum) to pull its mounting screws out, and that's a mess.

Bill

[oldstick]

Originally Posted by Bill

Oldstick -

I agree that a handle as you describe it would be handy. But let me caution against using the awning as a pull-down handle. The awning has been known (on this forum) to pull its mounting screws out, and that's a mess.

Bill

Yep, I understand. Usually, once I get the street side rear shell locked, the curb side will go down easily. Just a light hold above the awning for stabilization and the weight of only one foot on the stirrup. Then the front shell will latch both sides with minimal effort on the stirrups. But then again, handles all the way around would be great too.

[Bill]

Originally Posted by oldstick

But then again, handles all the way around would be great too.

Agreed. Like you, I tend to topple as I step up into the stirrup, so even a simple balance handle would be welcome. Maybe worth trying?

Bill

[Shane826]

Been thinking about ways to improve the lift design and perhaps make it easier to add lift assist mechanism... What if instead of using 2 L- shaped torsion bars at each end of each shell (so 8 bars total), they used 1 U- shaped torsion bar at each end of each shell (4 bars total)? This would eliminate binding caused by one side or the other being out of adjustment. Or, instead of torsion bars, they could just use plain U- shaped steel bars*. Put a gear on the middle of each bar and a motor with a smaller gear meshed to it, you have a simple torque reduction motor to lift or lower the shells. Take it a step further; locate a motor between the front and rear bars of each shell and use a chain & sprocket or jackscrew & gear setup from 1 motor to 2 U-shaped bars. There’s your automatic lift mechanism. One motor for the front shell, one for the rear.

*Not sure if the spring action of the torsion bars would cause a motor & gear mesh assembly to bind when the shells try to pop up when unlatched, thus just plain U- shaped steel bar with no spring load.

[Larryjb]

A "U" shaped torsion bar would have nothing to put spring tension into it, which is key to providin a lifting force. The small part of the "L" of the torsion bar locks onto the frame below and puts a twist tension in the bar when closed. A "U" shaped bar with a motor might be an idea, but if the motor ever failed 15 minutes before checkout time ...

I am a big fan of the simplicity of the TM torsion system. I still think my idea of a torsion bar that can provide even more lift advantage at the beginning is the simplest. As Bill said, more spring tension at the beginning of the lift will make it more difficult to latch down. That's why I was suggesting a latch down mechanism that would make it easier to close. This could be an assymetrical lever or perhaps a screw down system. A lever would be quicker, but perhaps more difficult. A screw down lock could be easier, but increase the setup and close down time.

[Shane826]

You could simply weld a tab on the middle of the U. Torsion bar springs on the front of a Chevy Silverado are straight lines, with a tab to catch the adjuster key. That was just a rough idea.