Linear Actuator needed

I need a linear actuator that can be mounted vertically to a wall or other surface and be able to support and lift about 100 lbs. Needs to
be compact and preferrably AC powered and reversible.
Some sort of Acme Threaded assembly might work also. I'm not an engineer but I know enough about all this to get myself in trouble. I've looked at linear actuators and most are very expensive. I just wanted to see if some of the brighter minds out there can think of something practicle and won't break the bank.
Thanks in advance for your response.
Ken
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Tv Sat. dish actuator with control box...
Like this on E-bay...
Item number: 180003148204
Item number: 280002396960
Item number: 250003109711
Item number: 290002126987
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kcleere wrote:

Hi Ken,
What's the application? It would be useful to know what you want to achieve before proposing any solutions.
Best wishes,
Chris
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The application is to assist a person to be elevated from near the floor to wheelchair seat height. A small seat would be affixed to the movable bed of the actuator which needs to be able to travel from about 4" inches off the floor to about 20" . The weight capacity needs to be about 150, not 100. Even more capacity would be great but that's all that's needed now and to keep costs down.
I would expect this needs to take up little real estate against the wall and may end up being mobile. Sort of a lift on a two wheeler concept.
Christopher Tidy wrote:

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This post is not to suggest a comprehensive solution to your problem, but to suggest that you think beyond a linear actuator. I find myself thinking of a light duty motorized scissors jack. Sort of like a motorized version of this: http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber9178
Vaughn
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I'm very willing to think outside the Actuator solution but I would like opinions if a LA would work.
Thanks for the Dish Lift view as well. Every time I see something someone else thinks of it helps my own thought process.
With respect to the dish lift in the link. Does the bracket shown mid shaft move up and down or does top of the thing come up out of the shaft...and...does anyone know what they are rated at for weight?
Vaughn Simon wrote:

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The top moves... I dont know what the rating is but some old dishes weight over 1000 lbs.
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The satellite dish jack/movers which have been suggested could provide a good solution, or at least a good concept worth considering.
I can't recall, but I think that 18" or 20" was the longest stroke available in the dish jack actuators.
The design consists of a screw inside two telescoping tubes. A mounting clamp is used to secure the jack's stationary section (the motor tube section). The adjustable end has an eye for affixing the moving end.
I think the jacks for the 10-12 ft. dishes may be rated at about 600 lbs, not because of the dish weight (the dishes are swung on bearings), but because the jacks need to be able to withstand wind loads of those big dishes (since many of them were solid, not screen mesh).
The motors are typically DC motors about the size of a windshield wiper motor, and may be 12, 24 or 36VDC. The gearbox reduction train doesn't need to be able to withstand any great stress because the jack screw is probably a ballscrew (low friction, mechanical advantage). I did find a Bendix motor/gearbox that utilizes an AC motor for use with the dish jack actuators.
I disassembled a flea market jack a couple of years ago, and discovered the ballscrew was working on ball thrust washers, so very little torque is required from the motor/gearbox. The ballscrew appeared to have a smooth rolled thread, and some type of treatment to produce a hard surface on the screw.
Probably not important to your application, but for positioning applications, the motor gearbox contains a feedback device for the drive circuits. The device may be a reed switch with a set of magnets arranged on a plastic disk, or a precision linear pot/resistance which varies with the length of the dish stroke.
WB ...........
kcleere wrote:

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Well...let me ask this...
My application would require that the platform lower to very near the floor. It appears the dish mover mounts with motor down and pushes the shaft up from the top? I don't know how I'd facilitate that.
Wild Bill wrote:

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Possible a small electric "winch" with power in/power out capabilities pulling on 4 cables going down from the support structure (seat could be on a framework with "tubes" on 4 corners, cables attached to the tubes and the tubes sliding up structure/framework tubes. HTH Ken.
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Garage door opener. Mount it to the wall. Add limit switches.
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kcleere wrote:

I posted pictures of that jackscrew assembly I picked up
http://pg.photos.yahoo.com/ph/gunnerasch4570/album?.dir=/2145scd&.src=ph&.tok=phKRJKFBf_LJG2TI
its a new or near new Joyce/Dayton 2 ton jackscrew assembly
Someone a couple weeks ago was asking how to pick up their mom or something while seated.
This unit would do it perfectly using a very small motor.
Ive got $50 in it, pay me that plus shipping and its yours.
If no response in a day or two..its up for grabs to anyone who wants it.
Might make a hell of a motorcycle lift actuator, welding positioner etc
the jackscrew is 1" in diameter and overall length is 36"
The L shaped plate on the traveling nut is simply bolted on and is simply removed.
Gunner
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