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markparker22 · 05-24-2004, 05:52 PM

In my 31 foot Excella I replaced the aft bedroom twin beds with a king size bed hinged on a metal frame. The two 120 lbs lift pistons, 20" extended, (Camping World, Suspa pistons) I installed do not come near the lift needed to allow the bed to be manually lifted open and remain open to gain access to the under-bed storage. (I have them mounted midway on the frames horizontally when the bed is down, with manually assist required to get them up to about 45 degrees.)

Anyone have any ideas on how to automate the lifting process? I've had to install a temporary block and tackle rope system to do the lifting (after my back gave out!)

Mark

74Argosy24MH · 05-25-2004, 07:26 AM

I used a 500 lb. linear acuator and made a lift for my bed but don't know if I will use it. I originally planned to use gas springs, after building this I think I might go back. It is heavy (not a problem because I have 3000 lb. to work with) and bulky (problem because space is at such a premium).

The springs come in much higher weights, I have seen them up to 500 lbs. That should give you a capacity that makes the bed a one handed operation with much less space and weight.

John

jaco · 05-25-2004, 09:43 AM

Hmmm

I never ever ever never fail to be amazed.
I should have spent more time with the Erector set years ago.

Marketing and engineering make the world go round. But then the question is what makes the bed go up...and stay...?

Gonna go (beam up) and look up linear actuator.
Hope this thread grows, it is interesting.

74Argosy24MH · 05-25-2004, 10:20 AM

A linear actuator is like an electric version of a hydraulic cylinder. Picture a motor driving a threaded rod with a nut on it.

John

markparker22 · 05-25-2004, 12:36 PM

John:
I did not even consider higher powered pistons/springs but was dealing with the biggest at Camping World. Will do a web search for stonger pistons. Your linear actuator I am sure looks complex because you found a way to get the rise needed. Most Jack actuators I considered only have a 12"-18" rise but could not hook them up to effect a big enough rise.

Happycampers · 05-25-2004, 12:58 PM

Mark, I built a Murphy bed last year from a kit. It has two gas cylinders and I can put it down and back up with one hand. It cost a lot but really works good, cost about 250.00 for the kit. Marvin

thenewkid64 · 05-25-2004, 01:16 PM

On the motor driven screw actuator don't think in one axis. I envision 2 motors working in tandem.

Mount the motor with a long drive screw parallel to the floor. The threaded drive bolt( I cannot describe it correctly) slider needs to be mounted to two equal length pieces of metal that are stout enough to support the bed. The ends will be mounted one to the floor and one to the underside of the bed platform. The hinge point will be the driven bolt on the screw gear. As the motor turns one way the bed lifts as it goes the other it will lower. This will also allow for a smaller motor as the arms should be acting as a lever and reducing the actual load you are lifting(maybe)

74Argosy24MH · 05-25-2004, 01:46 PM

Brett, I think I know what you are saying, sort of half a scissor jack mounted to the bed and floor. You can use one motor, reverse the voltage.

John

Tin Hut · 05-25-2004, 01:54 PM

If I put a quarter in it will it vibrate?

thenewkid64 · 05-25-2004, 02:05 PM

Quote:

Originally Posted by 74Argosy24MH

Brett, I think I know what you are saying, sort of half a scissor jack mounted to the bed and floor. You can use one motor, reverse the voltage.

John

Right. I was thinking 2 smaller motors to balance the weight and allow for side mounting along the longer length. I have a picture in my head, I just cannot find the right input to display it on the screen

markparker22 · 05-25-2004, 02:19 PM

Have found the Suspa-inc.com website with all sizes of gas pistons. My alternate plan was to go with additional 120 lb pistons in parallel because of the ease of buying them over the counter at Camping World. Will look at the Murphy bed kit concept also. Thank you.

malconium · 05-26-2004, 07:33 PM

Perhaps you could use a small 12' electric winch mounted underneath the bed. Consider using something like a very sturdy shelf braket mounted on the bottom side of the bed frame as close to the pivot hinge as possible. Ideally mount the bracket as near as convenient to the center of the bed frame or maybe mount two - one at each side of the frame near the hinge point. With two you would have a more complicated hookup to the winch cable and might need some pullys is all.

I recently bought a 2000 lb electric winch that had 50' of cable at Shucks Auto Parts for $79.00. There were cheaper models but this particular one was what I needed. It came with a bi-direction control switch and runs just fine off of a 12 volt battery. Check out ATV winches for possible models.

I am going to try attaching a simple drawing here for you to better understand what I had in mind

Malcolm

malconium · 05-26-2004, 07:40 PM

Trying the drawing again...

http://www.airstreamphotos.com/photo...cat/500/page/1

Over59 · 05-26-2004, 08:51 PM

A friend with a rather large MH has his King bed over the diesel engine. It was on two piston lifter to get access to the engine. Don't understand why this is a problem. Keep it simple so when you break it you can fix it.

mandolindave · 05-26-2004, 09:42 PM

Has it occured to any of you to try cold fusion ?

Over59 · 05-27-2004, 05:53 AM

Go Bio. 500 mices in those little cages hooked up to a pulley system. Give the cat something to do while you're at happy hour.
Prehaps your lifts are defective. When correct you should end up needing to push the bed down.

markparker22 · 05-27-2004, 11:32 AM

Keeping it simple is the right approach. A winch approach would use tremendous force if kept totally below the bed. I weighed the bed and it approaches 100lbs (on the edge) at the hallway entrance side with the other side hinged. Will be going with stronger pistons as this keeps the design simple and less space used under the bed. Thanks to all for the conversation.

Over59 · 05-27-2004, 02:12 PM

You may want to attach the base end a few inches lower to get it a better angle of attack. That way some of the force will be up rather than toward the foot of the bed.
If it requires 100 lbs at the end it will require 200lbs in the middle. I think those ratings on the pistons are in the vertical. You need to get out your trig book to figure the force at your starting angle to know if it offsets the weight at that point. Who said you wouldn't need this after high school.

markparker22 · 05-27-2004, 05:51 PM

Paul, you are correct. I have come to a similar conclusion on the angle and location of the base of the piston. I had a horizontal start before...now I know why my back went out with the 100 pound starting weight before the piston lift vector begins to do any good. (Those free body diagrams from mechanical engineering class weren't a waste either.) It is looking like 2 gas pistons, in the 100 lb. to 150 lb. class depending on a mid-frame mounting location and angle. I am leaning towards a much more vertical implementation if the cyclinder and stroke measurements of the pistons allow this with respect to the depth below the bed for attachments (14 inches max.)

By the way, the Suspa.com website gives an application sheet that asks for the required input data so they can work out all the trig functions, lift versus weight, etc. and then allows them to select the correct size and strength of gas pistons they manufacture.

malconium · 05-28-2004, 01:30 PM

Just a thought...

It occurs to me that you could also use something like garage door springs instead of an electric winch. Your king size bed is close to 7' long. If you had brakets near the hinge like in the drawing I furnished they would probably be something like 1' long. Put one on each side of the bed and that would be something like 350 lbs of spring needed on each side. Would garage door springs be a lot cheaper than the struts? I don't know...

Malcolm