Can a Pulley System Effectively Lift Patients Out of Bed?

[visitapatient]

Hi there,

I'm operating a hospital visitation program at the national hospital in Nairobi, Kenya.

I'd like to make a pulley hoist for lifting patients out of bed. Any suggestions on a pulley system which would effectively suit that job?

I'll be using metal pipes for the structure to attach the pulleys to and I'm still a bit unsure of how to make the base stable enough to support the weight of the patient while being lifted. Any suggestions on that would also be helpful.

I'm also happy with relevant website tutorial suggestions, as I've already done a bit of searching but I'm having trouble finding specific do-it-yourself tutorials. (most of the stuff I found is about lifting bikes or kayaks.)

I did manage to find a picture a patented hospital bed pulley system which I could use as inspiration for a design, but I'm having trouble understanding how the pulley system works. Every time I try to follow the rope I can't find where it ends! You should be able to view the image of the pulley system on the link below.

[URL]http://www.freepatentsonline.com/D285378.pdf[/URL]

Thanks a bunch.

 

[visitapatient]

It appears the image of the pulley system I mentioned in the post above didn't appear, although the code was there when I edited the post. I'll post it as a link instead.

http://www.freepatentsonline.com/D285378.pdf"

Oh yeah one other thing, how to attach it to the crank shaft thing!

 

[sundaylover]

Did you ever receive any assistance with your pulley system? I am trying to find a step-by-step diagram of how to thread my bike hoist and have gotten absolutely nowhere. I have seen a couple of videos on youtube but they are of much more complicated systems. I have a 2 pulley hoist. Thank you for any assistance.

 

[Danger]

Hey, Visitapatient;
For some reason, I missed this post until now.
As for the balance factor, I'd just run the bottom legs out far enough that the weight of the patient will centre the load. Being a totally lazy bastard by nature, I would equip the hoist with grippers that can simply clamp onto the edges of the patient's bottom sheet and use it as a sling to lift him/her.
A simple hand-winch such as you would find on a boat trailer will be more than adequate to lift the load.

 

[visitapatient]

Hi sundaylover,

Well, until Danger posted, no I didn't receive any assistance. I'm still looking for pulleys; they are hard to find here in Nairobi, unless I go to specific places which are a bit out of the way. I just got involved in like, 3 new projects so I'm really swamped with jobs so the pulley system has been put on hold for a while.

Besides, the guy I wanted to make the pulley hoist for died a week ago and the other remaining patients I have who actually need help getting out of bed are so sick that they weigh less than 50kgs anyway so it's no big deal for me to just pick them up.

Still, I'd like to finish the project at some point cause it could benefit some patients, I think. There was a woman a few months ago who was over weight, and had surgery on her stomach. The orderlies in charge of transfering her from her surgery bed to the ward bed had trouble picking her up to make the switch and in the process ended up dropping her.

Several days later, while at her home, her stitching came undone and her intestines burst out. She has since had surgery again and now she is ok, but what a traumatic experience.

I think a pulley hoist could really help people like that if one was readily available.

HI Danger,

Thanks for the advice and for responding, even though this topic is so old! I was thinking of using concrete slabs or bags of rocks to counter balance the base of the hoist and mounting the base on caster wheels so it's easy to move around.

As for the sling, I'll be working on an adjustable design which can lift patients in a seated position or in a lying down position. That will be a challenge in itself, but if there is no adjustability to the sling then I'll feel like it would be a waste to invest so much effort and expense on something that won't do the job for a variety of needs.

What I really need help with is the technical aspect of how to attach the pulleys. Pictures of pulleys in action would be helpful, if you know any websites like that. It's ironic, but in my searching on google I could really only find information about bike racks and kayaks, which SundayLover was asking about.

Anyway, thanks for the response.

 

[Danger]

To start with, I have immense respect and appreciation for what you are doing, and will offer whatever meager assistance I can.
What I was referring to regarding the balance point is along the lines of an engine hoist, which is used for pulling the mill out of a car. You should be able to find lots of examples of that via Google. (Actually, the design is very similar to a hospital tray table.)
As for the pulleys, you really need only two, both for directional change rather than mechanical advantage. (You can get by with one, but that introduces the possibility of the cable, chain, rope, whatever interfering with the load or in the other configuration having to reach quite high to work the winch.)
Think of the device as being constructed along the lines of a (North American) standard gallows. The outward side of the platform consists of a couple of runners like on a pallet jack, which can fit under the bed. One pulley is at the end of the top crossbar, and the other at the junction of the vertical member and the crossbar. From there, the cable goes directly to a hand-winch mounted on the lower section of the vertical member.
Anything that you care to use in the way of a sling or harness can be easily attached to the working end of the cable.

 

[visitapatient]

hi Danger,

Thanks for the response. I think I've understood what you are saying. I'll probably try to go for something like the example I originally posted. The pulley part of that picture is very unclear to me and it looks like it's using four pulleys, 2 side by side, which I think is too complicated for what I want. However, the basic structure looks good.

I did some searching around and found and example of a block and tackle moveable pulley (using two pulleys) on wikipedia. I don't know why I didn't see the wiki page on my previous search. Is it possible that I'm not as smart as the world thinks I am? :)

Anyway, I'll have to do some hunting around for pulleys and a winch, and then I'll practice putting it all together. I'll probably need some advice again when it comes to attaching the system to the winch but then maybe not, too. We'll see.

Thanks again for the comments. I'll let you know how it goes.

 

[Danger]

Oops! I had inadvertently overlooked your second post. The image link in your first one doesn't work, and I didn't see the second until you prompted me about it just now.
The complexity of the pulley system shown appears excessive; the mechanical lifting advantage of the block-and-tackle can be duplicated by simply using a suitably geared winch mechanism and a long crank handle.

 

[Cleonis]

Think of the device as being constructed along the lines of a (North American) standard gallows. The outward side of the platform consists of a couple of runners like on a pallet jack, which can fit under the bed. One pulley is at the end of the top crossbar, and the other at the junction of the vertical member and the crossbar. From there, the cable goes directly to a hand-winch mounted on the lower section of the vertical member.

I agree with Danger. A design in which a pulley system is used to get mechanical advantage is overengineered.

I agree that an effective design involves two pulley's, that are used to redirect the rope.

Large pulleys are better. The smaller the radius of the pulley, the more internal friction in the rope as it moves over the pulleys. If there is a lot of tension in the rope, and the pulleys have a small radius, then you need a lot of extra force just to get the rope "around the corner", so to speak. Also, if the pulleys have a relatively large diameter the stress on the pulley is less, putting the material under lower load.

As Danger writes, give the drum of the winch a small radius, and make the crank long; that's where you get the mechanical advantage.

The winch, will it have to be manufactured locally, or are there funds for buying an 'of the shelf' winch?

Lifting is secured by using a winch with a ratchet. But you also need to lower patients down safely; it seems to me that is a more difficult issue. Some mechanism to introduce friction would be helpful. If you can I suppose you should buy a winch with an extra lever that operates some internal braking mechanism. If the winch must be manufactured locally, then I do recommend to try and find a way of adding a braking mechanism, acting either on the winch drum or the rope itself (of course the braking mechanism must not damage the rope in any way.)

A crude but (I expect) effective braking mechanism that acts on the rope is to have the rope run in between two plates that can be pressed together, with a long lever helping to exert the pressure on the rope.