Linear actuator

[gordy87]

Thought this might be a good place to ask this. I'm building a scissor lift for my garage, capable of lifting 200kg ish. I bought a 24v hydraulic pump and was going to buy a ram and pendant remote. However I've just come across an electric linear actuator capable of lifting 300Kg. Its a gate opener but should work. It will be much neater, quieter, lighter, cheaper and hopefully less hassle.

I've seen how to wire up an actuator with 2 wires to a rocker switch but the actuator I'm looking at has 4 wires. I'm trying to get my head around the 'common' wire.

Is this diagram below how the actuator would be wired up or am I nowhere near?

 

[RF Lighting]

Does it not come with any instructions?

I’d imagine the common wire will connect to your neutral supply wire, and you will need a two way centre off retractive switch to operate it. Something like this https://www.tlc-direct.co.uk/Products/MKK4900.html (plus a grid frame, plate and backbox) should be ok.

Does the ram have inbuilt travel limits? If not you’ll need to think about how you stop the ram being powered when it reaches the end of its travel to avoid damaging or burning out the motor.

 

[flameport]

Gate actuators usually have an external capacitor connected between the 'open' and 'close' wires, common is neutral, and line is connected to either open or close depending on the action required.

 

[rsgaz]

A 2000N load, with the scissor arm in the closed position (i've gone for 10 degrees), needs a force of over 11000 newtons, just to stay in equilibrium, let alone raise anything.

Your gate closer won't cut it, sorry.

 

[gordy87]

Thanks for the replys.

So Is the common wire always neutral in all applications? Or do you need the wiring diagram to figure out which wire is the common?

There are instructions but they are terrible and show no wiring at all.

The limit switches or lack of shouldn't be a problem as the ram will be fixed in position so it will only travel a certain amount. Which will be less than full travel.

Rsgaz, thanks that's good to know before I go down that route. Do you have a program for calculating forces? What if I connected the ram like this picture and didn't do a scissor lift?

 

[bernardgreen]

The limit switches or lack of shouldn't be a problem as the ram will be fixed in position so it will only travel a certain amount

If the power is not switched OFF when the ram reaches the end of its travel then the stalled motor will almost certainly burn out in a very short time.

There are rules about the design of a lift. These rules are there to try and ensure that the lift cannot cause injury or death if the operator is careless in using the lift.

 

[conny]

We used to use pallet lifts at the end of the production line in my last place.
Before servicing/repairing them we had to raise it to a certain height, (this was done by motor driven chains which lifted it squarely on rollers inside guide rails. We then had to insert 2 1/2" steel pins in the 4 corner posts and then lower the lift to within 1" of the pins. If, by some freak incident, any or all of the chains snapped the pins would stop it going any further.
You will need some sort of similar safety device for your hydraulic lift.

 

[oldbutnotdead]

You're going to be much better off either buying a motorcycle lift or redesigning your scissor lift so the lifting effort is provided by a trolley jack or similar (a very clever local chap built us a piano lift working on similar principles so we could get a 6' Steinway onto 3' staging. Top of the instruction sheet - NEVER GO UNDER THE PIANO WHEN THE LIFT IS HOLDING IT).

EDIT Just buy a lift if you're asking strangers on a web site to design it for you. Either design (scissor or trapezoid) will involve substantial loadings at pivots and energy input points. Have a look at motorcycle lifts & see how chunky those key sectiond are

 

[Tigercubrider]

A Chinese motorcycle lift is the way to go.
Either hydraulic using a jack, or screwjack if you have a motor.

My hydraulic bike lift only goes up about 500mm as it's one of the under engine ones.
That has locking pins.
I also have one that uses a screw thread that you could power with a drill. That only goes up about 350mm

A big table top type is too big for my garage but is about £350-400

 

[gordy87]

I already have a home made bike lift which I use a trolly Jack to raise. It has an arm that swings down on a pivot and ratchets over blocks to stop the table falling in the event of a failure. This new table will employ the same system. But will be safer with a ram of some sort.

The Chinese tables are flimsy rubbish. This one I'm building will be from 40mm box section with 20mm sleeved bushes and bolts for pivots. It will also have a bigger area on the top. And the whole point in it being a project was to learn a bit on the way. Bit of welding, machining, hydraulics, electrics etc. I'm well aware it needs to be safe, I wouldn't be putting my pride and joy 2 foot in the air if I wasn't confident