DIY Converting a manual penthouse to electric (A possible solution?)

[arctictraveller]

This is all very interesting. My GTRV top uses gas springs, I wonder if you could add a couple of them inboard of the springs. I had a hatch on my boat that was crazy heavy and hard to open, but with a couple gas springs it now opens with one finger. Just a thought.

 

[boywonder]

I got myself a spring scale. I measured about 170# to get it moving.

Including your weight?? If that's in addition to what you weigh that seems like way too much.....

 

[Flakwagon]

Including your weight?? If that's in addition to what you weigh that seems like way too much.....

170# in addition to my weight. Like I said this thing is heavy. But Once it gets going it's easy. I remeber it being pretty difficult to lift in the donor van as well. I'm pretty sure I put everything back together correctly. When I did the shoulder bolts through X of the lifting arms they moved pretty freely. The currently shuttle design is the only thing that has alot of friction.

 

[BUFFALO-SMB]

My top is very hard to lift also. I seem to remember when the van was new to us that it was much easier.
So you are shoulder pressing a 170lb top? I couldn't do that I'm pretty sure.
Is it possible something is binding? Can the springs weaken over time?
That just seems like way too much to expect someone to lift each time.
I see why you are so motivated to make this work.
I'm following with interest.

 

[Glider-ClassB]

I have not had an easy time getting my top to move upward. After the first 12" it is fine, but the first 12" takes significant effort. For reasons I do not know, it was not that way at first, but it has become progressively more difficult over the past few months.

My solution: I pull out my gaucho about 6", then I lay the gaucho back on top of the seat for some added height. I then lie down on my back, and put my stocking feet against the PH top. It is a reasonable leg press to get it up the first 12". After that, I can stand up and guide the top's rise the rest of the way with minimal effort.

Interesting note: when the top is up, I hang all 115 lbs of myself from the handles to get it to start moving down. Once it starts moving, it comes down quite nicely.

Maybe this is mostly about friction. At the moment, I do not know.

 

[Nrobert10]

Mine does not have anything on top of it but I would guess it's less then 70# of pressure before it goes right up. For sure no way on mine it's 170#

 

[larrie-SMB]

I once put a bathroom scale under my cargo bar lift system. I remembering it being in the 70# range just before the springs took over.

 

[Tapatio]

I tried and failed with similar approach. Huge amounts of force needed.

http://www.sportsmobileforum.com/forums/f34/best-way-to-raise-penthouse-12529-3.html

 

[boywonder]

I'm struggling with 170lbs to lift the top, even with mis-adjusted springs....

I doubt that I can press a 170lb barbell........

70 lbs maybe......I'm visualizing pressing a 90lb bag of cement mix over my head...heavy...

I've been traveling for work for the last 3 weeks, otherwise I would have already put the bathroom scale in the van......

 

[Flakwagon]

I tried and failed with similar approach. Huge amounts of force needed.

http://www.sportsmobileforum.com/forums/f34/best-way-to-raise-penthouse-12529-3.html

This thread is more helpful than I could have hoped. Thank you!

The approach someone in here used involved 2 actuators each pushing 150# vs 2 actuators each pushing 1100# I am proposing. With the angle of the bars closed the force applied to get the 276# assembly moving totals nearly 3200#

Someone in there has a link to a set of scissor lift equations and model.
Scissor Lift Jack Force Bottom Load Calculator | Engineers Edge | www.engineersedge.com

This is the model I am using to work this out. There is a set of free body diagrams in there as well if you dig far enough.

I havent given up on this but something seems very off with my top. 170# is alot of force require to get this thing moving. I checked again using a hi lift jack to take myself out of the equation. Pushed nearly 200# with my jack and blocks of wood weighing about 35#. so the 170# is about right

I did calculate my top to weight 276# which sounds about right based on how heavy it was to move around.

I do have strong reason to believe that friction is working strongly against me. I think the current design is binding. Even when I found the point of neutral buoyancy where the top would sit still, It would still take me nearly 60# of force to move the top in either direction.

The conclusion I am coming to is that with the 1100# actuators and the main springs all working together would give me a total of 3102# of force. the load calculator says I need 3162# of force to get it moving. Which means this idea would probably not work. Even with the top empty the numbers are too tight. Never mind the solar panels and cargobox I wish to add.

I am now leaning towards the use of a hi lift farm jack to get it up. It is a bit of a trick that I wanted to avoid, but I can at least do away with my bottle jack, and use this as a winch if needed.

All that being said, This topic is still open for discussion. Im still toying with other ideas for actuators and something that could be a simple push button solution.

 

[Flakwagon]

Oh and to address the earlier questions of how Im working this thing now, Im doing a combination of a shoulder press and a leg press. Im in really good shape and this is still pretty hard to do. But if I ever have a day where my back is bothering me, it wont be going anywhere.

Check out the hi Lift jack set up I rigged up real quick. It would look alot cleaner If I decided to make this a more permanent solution.

 

[Nrobert10]

Ok so I did the same experiment lifting my top this weekend with both my weight and a jack. I have an EB pop top with no racks or anything on top. Springs have full length chains and not blocks behind the springs.

With the jack I had a total lifting weight that never exceeded 150#'s. That weight is including the jack and lumber that weighted 46#'s. So total lifting weight of 104#'s.

When I tried it with my house scale and my body weight it was much harder to watch it very detailed but I came up with 94#'s after removing my weight.

 

[berns378]

I bought a assit lift from sportsmobile 12 years ago for under 400 dollars.had to replace fuse twice. takes less then 30 seconds to lift top. I have two solar panels aluminess light bar with four lites and a go light. also a sky box loaded. very heavy but no problem with the lift.

 

[boywonder]

Nrobert: I briefly met with Flakwagon yesterday and did some bathroom scale lifting...he has an EB with three links out of the chain and we got readings a little higher than yours.

His top will stay in place where you put it and it will move near the top of it's travel with about 60 lbs. To start lifting it from full down took at bit more than what you are showing above....I think around 140-160 lbs.

He needs more preload on his helper springs.....and the more I think about it longer springs would help greatly as well.

His top is a mid 90's and the helper springs are shorter than the springs in my early 2000's RB top. Any chance both you and Flakwagon can measure the length of your helper springs? I will measure mine when I get back to So Cal next weekend hopefully.

 

[Nrobert10]

I will measure my helper springs but wont be able to get to it until this weekend as my van is in a barn where I'm doing my 4wd conversion.

 

[Nrobert10]

So my helper springs are 12" long.

I remeasured the weight again this weekend two different ways. One without the helper springs and one with them.

Helper springs removed jack and wood was 35#'s. The max weight of the lift was 185# total including the jack and lumber. This was about 4 clicks up on the high jack.

With the helper springs in it was 148# including the jack and lumber.

My top will also sit still and not raise also if you are above the first 10-12" of lift.

 

[CreekRob]

Has anyone ever used a trailer jack? like the stabilizer/leveling jacks on campers? They have electric versions as low as $150 or so, Electric Jack w/ Footplate - Drop Leg - A-Frame - 25-1/8" Lift - 3,500 lbs - Black etrailer Camper Jack EJ-3520-BBX. Kinda bulky, but might have a use elsewhere in the van which would make it worthwhile to have.

 

[boywonder]

...Just measured my helper springs.... 23.5" long

 

[Flakwagon]

Sorry I've been offline, I've been busy trying to get my build finished! About a week out from completion! But yes I did meet with boywonder and I added 1.5" wood blocks behind my lift assist springs. That has taken my initial lift weight of 170 down to 130. This has made it Much nicer getting up and the top almost pops up on its own after the initial lift. Solar panels are going on this week so we will see how that affects it. Me and Katie have been doing a team lift effort lately where we each push up on one of the vinyl pads at the same time. This takes minimal effort and makes me think we have plenty of room left for solar and cargo on top.