DIY Bed Lift (Happijac alternative)

[BradKW]

I've been stuck on the idea of a bed lift for as long as I've been wanting to build an RV. One of the first RV conversions that really struck a chord with me was the Aussie Stealthsprinter ( http://www.stealthsprinter.com/van-build/finished-van-photos/ )...the way they were able to leverage vertical space using a Happijac lift allowed for a spacious lounge and living area.

The problem comes in when one begins trying to shop for a Happijac lift. They are only sold through dealers and you're basically looking at $2,000 with tax + delivery...and that is quite a bitter pill to swallow for something that straddles the line between optional and necessary. Depending on how you look at it of course.

So I've come up with what looks to be a very promising alternative...and when I say "I", I mean I am flat out plagiarizing someone else's idea. That person is Berk8520 over at the Transit forum, original thread posted here:   http://fordtransitusaforum.com/camper-vans-conversions/21953-advanturing-build-3.html#post286521

The basis of this system is a Racor cable lift, here for $131 at Amazon: https://www.amazon.com/gp/product/B0009I8AO6/ref=ask_ql_qh_dp_hza

Notice that he's installed the system in reverse, with winch underneath the platform. And the plywood platform is just a test model.

So for $131 I just ordered one...figure it's a solid concept I feel confident about adapting, and minimal risk.

I would like to set up an electric motor for it, so any suggestions would be appreciated:

The one thing I want to add is a 12 volt motor and a switch to lift and lower without the drill.  What I don't know is how to spec a motor that will work for this application and where to buy it.  If anyone has some advice on that it would be greatly appreciated.  My dumb guy  math goes like this.  The pulley crank turns 1 time for every 16 rotations of the drive shaft.  That means a 16:1 ratio. My bed fully loaded probably comes out >75 lbs so call it 150 lbs to be safe.  That means the motor need to be able to apply 9.4 ft pounds of torque to turn the crank.  So where do a find a 12 volt motor with 20 lbs of torque. I also need a three way switch for the motor.

Berkeley

 

[ViaVacavi]

That's really cool!

 

[BarryinSeneca]

You've got a lot of room to work with, but to me, the kit doesn't offer a lot.  And, by the time you buy a drive motor and the reversing relay, you could easily buy a winch.

My project is a Nissan NV-200 that I've stretched 30".  That gives me room for a full-sized bed, but not a lot of head room.  Of course, I want storage under it and to make a little seating/table area at the wheel wells.

I like your project and it's a similar design to the overhead Doozie Boat lift that I installed for a neighbor.  ( http://www.itsadoozie.com/content/pontoon-lifts).

I didn't want Happijac's straight vertical bars or overhead structure with my van's curved walls and ceiling.  Like you, I didn't need to support the bed as the cabinetry beneath it will do that well enough. And I didn't need to keep the bed perfectly support when it is up as the mattress pressing against the ceiling will do that.

So, I bought a $50 (on sale) 2500# (overkill) winch from Harbor Freight and mounted it on the left side of the van, under the bed.  I removed the cable and made a plastic divider for the middle of the drum.  Two 1/4" dacron/kevlar  ropes go straight up to a double grooved pulley on the top left corner of the van, approximately centered on the bed. (The ropes are protected from interference with split poly tubing.) One rope goes down to the center, left side of the bed frame.  The other rope passes overhead through a tube to the right side of the van to a  pulley and down to the center, right side of the bed frame. This way I'm lifting the bed not by the corners, but by the middle of each side.

The winch has a wireless remote control and runs on 12vdc.  The winch doesn't have a drum lock.  However, with my light load, and the winch's high gear ratio,  the bed doesn't un-spool the rope when the motor is off.

When raising/lowering the bed, I simply put my hand on the end of the bed to stabilize it and press the button on the remote.  You just have to watch that you don't allow the winch to pull too hard and break the rope/pulleys. But, so far, that hasn't been an issue.  (I did intentionally use some undersized, high-temp wire from the relay box to the motor to act as a resistor to reduce the maximum winch torque.)

I chose attach the the winch to the side of the van rather than under the bed's deck to avoid the winch's power cable getting caught on something or wearing.  I also didn't want the rope/cables to suck stored clothes (or whatever) into the below-deck winch or pulleys.  

And finally, my frame is a few inches smaller than the mattress. this lets the bed squeeze in firmly at the curved edges of the ceiling.

 

[BarryinSeneca]

You want a cheap motor to replace the drill???  How about a drill??

12-14VDC rechargeable drills are easy to find at the flea market or even Harbor Freight.  Usually you can get them for $5-10.

Open the drill up and find the leads going directly to the motor.  Cut them away from the variable speed trigger or reversing switch and run the wires out of the case.  Run them to a DPDT switch with  Momentary ON -- Center OFF  -- Momentary ON positions. Make sure it is good for at least 15A.  

Connect the switch's center two terminals to the motor wires.  Connect the 12V + and - wires to the terminals on one side.  Then connect the 12V - and + to the terminals on the other side.  Make sure you include a fuse and you are good to go.

Mount the drill with shelf brackets or wood blocks and worm-gear hose clamps.

Not pretty, but cheap and it works.

 

[BradKW]

Sounds like a nice concept...maybe you could post some pictures? Hard to visualize all that...

 

[JulesW]

You want a cheap motor to replace the drill???  How about a drill??

12-14VDC rechargeable drills are easy to find at the flea market or even Harbor Freight.  Usually you can get them for $5-10.

Open the drill up and find the leads going directly to the motor.  Cut them away from the variable speed trigger or reversing switch and run the wires out of the case.  Run them to a DPDT switch with  Momentary ON -- Center OFF  -- Momentary ON positions. Make sure it is good for at least 15A.  

Connect the switch's center two terminals to the motor wires.  Connect the 12V + and - wires to the terminals on one side.  Then connect the 12V - and + to the terminals on the other side.  Make sure you include a fuse and you are good to go.

Mount the drill with shelf brackets or wood blocks and worm-gear hose clamps.

Not pretty, but cheap and it works.

I guess it would also be possible to use the drill with a suitable bit to connect to the mechanism underneath and then you still have a working drill for odd jobs around the vehicle.
I also would like to use webbing used for car seat belts. It is soft, wear would be easy to spot before a corner totally fails, readily available and cheap. The webbing could wrap around the central shaft and pulleys would just need to be some sort of broad roller with bearing. It could even be coordinated to the colour scheme if black is found to be too dull.

 

[Redbearded]

I love this Idea!

I was having the same idea about using the webbing instead of the cable, though I just didn't want my dog to get himself caught in the cables.

 

[MikeRuth]

I'd love to see some pics and or video as this concept to me seems to prevent cabinetry or counter top.

Mike R

 

[John61CT]

Some videos mentioned here

http://tnttt.com/viewtopic.php?t=69353