Bed to ceiling hoist with wiper motor, risk of failure and collapse?

[cormie]

Hey folks,
I found this forum after looking up Dyneema rope and saw a post here with somebody looking for advice on hoisting boats with a winch. The replies were very helpful so I thought I'd join to seek some advice on my project.

I'm in the process of changing from a manual winch, to a 12v wiper motor, to hoist my bed in my campervan, to the ceiling. Although I've never been 100% confident that the system won't suddenly fail at some weak point with the manual winch, it's survived until now, although not with a lot of use.

I've now motorised the system with a wiper motor:
Model: ZD1633R
Power: 100W
Voltage: 12V
Rated Speed: 50RPM
Rated Torque: 8N.m
Reduction ratio: 61:1

It is lifting and working, but I'm still a little nervous using it and not 100% confident it won't collapse and fail if there's a weak point(s) in the system.

There's approximately 40kg of a load. I believe the motor itself can lift 100KG, however with vector forces etc (which I only found out about recently), I'm just a little concerned the force exerted at certain points may exceed break load.

With indeterminable load and indeterminable break load, If anyone would be able to advise on how the system appears from any experienced eyes, it would be greatly appreciated.

I've uploaded a video to explain better here:

Since posting the video, I looked into some redundancy solutions should the system ever fail and think I'll add at least one of these Progressive Capture Devices for the rope: Zelts eil spanner langlebiger Seils panner für Camping zelts chnur anpassungen starke tragende leichte tragbare Schnalle - AliExpress 18

And then I'm trying to figure out would Dyneema rope be better than the likes of WaveLine nylon rope.

I look forward to any input at all

 

[Metalicmike]

Use your winch to raise the bed then secure it with a fixed line.

 

[cormie]

Use your winch to raise the bed then secure it with a fixed line.

Thanks for the suggestion, but the idea is to replace the manual winch with the motor hoist. Once it's hoisted to the ceiling, I already have a solid method of securing it for driving. It's just the worry I have during the actual process of hoisting it that I'm hoping to resolve. The worry was there with the manual winch too, I'd just like some reassurance and to put in whatever measures necessary to avoid failure

 

[MontyMariner]

concerned the force exerted at certain points may exceed break load.

Incorporate a ratchet, maybe with a solenoid release system.
Think boat trailer winch.

 

[cormie]

Incorporate a ratchet, maybe with a solenoid release system.
Think boat trailer winch.

Thanks for the suggestion, sorry I'm quite inexperienced with any of this so just learning as I go along. What would a ratchet do in this case? Would it act similarly to a progressive capture device, that if there was a failure in the system, the ratchet would stop the load from falling? Then if I want to lower the load, release the ratchet with the solenoid? I guess the system could also fail when being lowered, but I guess this is far less likely.

 

[MontyMariner]

Thanks for the suggestion, sorry I'm quite inexperienced with any of this so just learning as I go along. What would a ratchet do in this case? Would it act similarly to a progressive capture device, that if there was a failure in the system, the ratchet would stop the load from falling? Then if I want to lower the load, release the ratchet with the solenoid? I guess the system could also fail when being lowered, but I guess this is far less likely.

I think you could class a ratchet as a progressive capture device and stop the load from falling.
As we are talking campervan, the solenoid release would just be bells and whistles as you can easily reach a campervan roof to release a ratchet. Lowering the bed won't put much strain on the motor so it is much less likely to fail on lowering, plus you're less likely to be standing under it.

 

[rogerthebodger]

most wiper motor gear box are worm drive gearbox and as such tend to be self-locking and will not run back.

I have designed and made various activators on my boat including ball valve actuators and an actuator on my engine to operate the run /stop lever

I have used then as screw actuators on hatches open /closers

Ratchets can ware and slip so I would avoid ratchets and would use a roller chain and sprocket in the wiper motor as the way to lift the bunk to prevent any possible of falling down.

You will also need some top and bottom limit switches and relay controls to control the up and down operations

https://flic.kr/p/WYNn74

https://flic.kr/p/VKkRZx

 

[cormie]

Thanks again for the replies folks! Yep I can easily reach the ceiling so if I need to manually release a catch to allow the bed back down, that's no problem of course. I'm already releasing 4 other catches that clamp the bed to the ceiling during transport

Yes, I'm not so worried about the wiper motor releasing the load, unless there's too much strain for the shaft, but I'm hoping it can easily manage the 40kg. My worry was more if the entire wiper motor was ripped from the support wall, or if the eye plate and the other pulley point happened to tear out of their hold.

@rogerthebodger by the limit switch, do you mean to prevent the bed going too high and the motor pulling the load too far? I'm actually using a remote/portable up/down switch with the wiper motor, so I can guide it up while paying good attention to the height, but it has happened where I very briefly press the button, but the motor runs for a second or two longer than expected, so this could potentially cause issue. I'm not sure how easy this would be to limit the point at which is turns off, but I think I might get away with just eyeballing it and I will stop the motor with a bit of buffer and then just lift each side of the bed into position with the clamps which is easy. It would be nice to have it cut off automagically at a certain height, but this would be way above my ability.

 

[rogerthebodger]

Thanks again for the replies folks! Yep I can easily reach the ceiling so if I need to manually release a catch to allow the bed back down, that's no problem of course. I'm already releasing 4 other catches that clamp the bed to the ceiling during transport

Yes, I'm not so worried about the wiper motor releasing the load, unless there's too much strain for the shaft, but I'm hoping it can easily manage the 40kg. My worry was more if the entire wiper motor was ripped from the support wall, or if the eye plate and the other pulley point happened to tear out of their hold.

@rogerthebodger by the limit switch, do you mean to prevent the bed going too high and the motor pulling the load too far? I'm actually using a remote/portable up/down switch with the wiper motor, so I can guide it up while paying good attention to the height, but it has happened where I very briefly press the button, but the motor runs for a second or two longer than expected, so this could potentially cause issue. I'm not sure how easy this would be to limit the point at which is turns off, but I think I might get away with just eyeballing it and I will stop the motor with a bit of buffer and then just lift each side of the bed into position with the clamps which is easy. It would be nice to have it cut off automagically at a certain height, but this would be way above my ability.

It could be easy for you to eyeball the position but what about others.

On my stern hatch I have a remote control so I could eyeball it but still have limit switches to prevent overload.

In your case to prevent the possibility of shearing the wiper motor drive shaft or to pull the wiper motor from is mountings and the bed falling down onto the operator when going up its about safety

The second pic shows limit switches on my seacock actuators. The limit also provides a switch to show that the motor is at the end of its travel which is important on the seacocks as I cannot see the seacock so I cannot eyeball the operation

 

[cormie]

Thankfully I'll be the only person operating it so I wouldn't have too much concern over that aspect. It would definitely be good to have the limit switch, especially not to rip anything apart if it goes too far, I learned the hard way when testing another hoist system using another wiper motor in the van already

Would you know what I'd need to add those? How is it programmed to stop at a certain height? Does it need an onboard computer of sorts? I'm actually due to go to my electrical guy tomorrow or Wednesday, he could probably integrate them, but I'd want to have the parts ready to go for him I guess, haven't a clue what I'd need though

 

[rogerthebodger]

No computer required I have just used 2 change over relays with 12 V to one side of the changeover contact and 0V to the other and the motors + and - connected to the common of the switched on ach relay.

Powering one relay will then cause the motor to rotate one way and powering the other relay will power the motor the other way.

The - to the relay coil is the wired to the closed side to the limit switch which have a changeover contact

Limit switches connected in the black wire to the relay coil.

I will look for a better circuit

 

[cormie]

Hey thanks again for the continued input! Unfortunately electrical stuff goes over my head. I know my electrical guy did put it on a relay, to allow the motor to go up and down via a remote control. I think it was all done with this set: https://amzn.to/4gHL8BT

Are you saying in what you've described above, there's a way for it to cut off once the motor does a certain amount of rotations or somehow that it will know to cut it off before it goes too high?

I will link my electrical guy to this thread and hopefully it won't be too difficult to retrofit!

 

[rogerthebodger]

That winch remote control will do the job, but I think it's a bit overkill for what you are planning.

We use door/gate remote controls at our house to open and close Garage doors and driveway gates thre are mains appliances but the remote is powered by 12Vdc and Battey in the remote the remote receiver simply drive the relays as in the pics I posted

That winch remote control is like the one I use on my boat winch which is much higher power required than a simple wiper motor

 

[MontyMariner]

Are you saying in what you've described above, there's a way for it to cut off once the motor does a certain amount of rotations or somehow that it will know to cut it off before it goes too high?

Shown as Limit Switch in Roger's circuit diagram. Google Limit Switch for chapter and verse.

 

[rogerthebodger]

Shown as Limit Switch in Roger's circuit diagram. Google Limit Switch for chapter and verse.

The limit switch cuts off the power to the appropriate relay thus stopping the motor rotation in the selected direction

The common of th elimit switch is connected to the negative of the relay coil and the NC is connected to the negative of the supply.

The operating switch is connected to the positive side go the relay coil and the operating watch feed + dc to the positive of the coil

Sorry easier to draw that to describe

 

[cormie]

Just to say thanks again for the help on this. I haven't really progressed much since. My electrical guy will know what to do if I show him the above I guess, unfortunately it's all going over my head. In the mean time, I will just be very careful to stop it well before it will go too high, and then just push it into place to secure with my hands with the bit of slack left.

As regards the vector forces and the strength of the fixings, I'm just hoping that will all be ok too!

 

[Metalicmike]

Wasn't relevant