Drive multiple hoists utilizing one motor

[jchanna]

Objective:
Drive multiple hoists utilizing one motor.

Description:
Our industrial space is outfitted with multiple joist-mounted hoists for loads of 50-150lbs each. Each rope-wound pulley terminates at a single control wall, where they are lifted and lowered by hand. We would like to convert this manual system to a semi-automatic cable system and add a motor controlled by a switch box. The motor would power each hoist asynchronously, controlled by the switch box.

Questions:
What type of motor head would drive several different cable-wound pulleys independently and asynchronously?
Who might manufacture a switch box that could control this system?


I'm not sure if this is the correct forum for this; in fact, I'm not even sure I'm asking the right questions. I was hoping one of you could direct me to the correct equipment or resources needed for me to start to narrow down what it is we're looking for. Also, any help with the correct terminology would help me zero in on search, so far several hours on Google have been fruitless. Any direction would be a huge help. Thank you in advance.

 

[drawoh]

jchanna,

I think any motor would work, as long as you can control it.

Each lift would require a power-on clutch and a power-off (dead[ ]man's) brake. Are you sure this is cheaper than multiple lift motors? I suspect that there is something off-the-shelf that functions as a hoist actuator, that combines all the functionality you require, and that is reliable and cheap enough that you can order one for each hoist.

Who will the 150lb weights land on if the system fails?

--
JHG

 

[MikeHalloran]

Forget one motor for muliple hoists; you will need a clutch and a brake for each hoist, they need to be coordinated with each other with specialized controls, the clutches and brakes will require maintenance, and you will inevitably need two or more loads lifted simultaneously. It's a much bigger headache than you want.

If instead you use multiple single hoists, you can just unhook a broken one and repair it offline, or throw it away if you get cheap ones.

... but there are better solutions...

For loads as small as 50..150lb, you should look at individual 'tool balancers', which can be powered by air or electricity, and are a lot easier to use than anything you have so far imagined.

If even those are too expensive, I'd look at multiple long stroke air cylinders, each hung from the joists at each station, with air applied to the rod end by a manual valve at the workstation.

IMPORTANT: If you're hanging more than one workpiece per joist, or your hoists are particularly heavy, please get a local qualified structural engineer to review your installation plans to make sure you don't accidentally compromise the building structure.








Mike Halloran
Pembroke Pines, FL, USA

 

[jchanna]

Thank you drawoh and MikeHalloran, It looks like you both replied simultaneously advising against a single motor.

The idea was to spend the research and expense up front to build a system that would make things easier for sustained use, but it sounds like it would actually be more work up front and more work down the road. I have a tendency to overcomplicate things. Glad I consulted with you guys.

I'm going to take a look at the tool balancers and long stroke air cylinder as a potential solution, thank you for the suggestion.

(Re: Safety - The manual system in place was checked off by a structural engineer. I will also have the new system looked over before installation)

 

[BUGGAR]

I like those vacuum lifts - the elephant trunks with the vacuum motor above that lift by suction. You can move things laterally a little also. And their fast lifting.

 

[3DDave]

When the plants were run from a single large waterwheel, there were a ton of belts. It think they used tensioner pulleys instead of clutches. The tensioner tightens the belt and the drive is engaged; loosen the pulley and the belt goes slack. The shaft speeds couldn't have been very high, so the friction of the belt loose sliding on the smooth drive pulleys would do no harm. I think the same can be seen in steam farm tractors at antique shows.

I think they didn't need brakes as those factories were running rotating machinery and would stop on their own.

There's a reason factories aren't like that anymore.

 

[chicopee]

Jchanna, if you still pursue this 17th and early 18th century technology due to economic constraints, dig up some earlier mechanical engineering handbook such as Kent probably no later than the eleventh edition which was passed down to me from my uncle some 40 years ago. There will be a fair amount of information that describes clutches, material for hoisting and driving, arrangements, etc... The system that you described is heavy on maintenance which is one good reason it is no longer used in most countries.

 

[dhengr]

Jchanna:
For the most part you deserve the responses you have gotten, because you have so inadequately described your problem and the layout of the various hoists, or really even what the hoists are. Some sketches, plans and elevations of the layout various hoists might be helpful, plus info. on the hoists and their rigging, if you gave it a little thought. We really can’t see it from here, and your word picture could conjure at least eight thousand different arrangements, none of which fit your situation. At the common control wall, I would turn the wire ropes from the various hoists down the length of the wall to a common location. At this location one motor, through a bunch of gear boxes (winch drums) or some such, maybe radio controlled from the work stations could operate all the asynchronous hoists. I would run all the wire rope lines to the common location, up high on the wall so as to keep them safely out of the way of the workers, and then turn them down to the motor/gear box level at this location. This whole system probably has to be guarded in some way, so workers can’t get tangled up in it, see OSHA. For the kinds of loads you are talking about, you could buy an inexpensive, pick-up truck type winch system, or something similar, for installation at each hoist location. This would likely be much safer, controllable at each work station and usable while other hoists were in use, less maintenance intensive, and you would probably save more than the cost of each of these hoist motors, in extra sheaves, wire rope length, gear boxes and drums anyway, etc.