Car Lift Light Beam kill switch limiter

[jsimon77]

Hi All,

You have all been amazing helping me figure out the lift in my garage.

I'm getting an AC Lift single post installed in 2 weeks.

I wanted to find out of anybody has seen or install some kind of kill switch or limit switch that would shut the motor off IF you went to far up.

I was thinking it could be done like the light beam for a garage door. If the beam is broken it will kill the motor?

I've also seen a mechanical limit switch but wondering if anybody can point me in the right direction for the like beam option.

Thanks!

Jason

 

[Dustball]

Depends on how knowledgeable you are with AC/DC circuits. It's going to be difficult for someone to explain to you how to do it without knowing the exact internal wiring of your lift.

Could probably adapt something like this in combination with a relay-
https://www.amazon.com/dp/B001LFPB0M/?tag=atomicindus08-20

 

[finn]

My two post lift has a hinged limit bar and a microswitch to cut power.

Don’t they all have something similar?

 

[Doug Arthurs]

It would be pretty easy to use an industrial photo eye for this. Many of the machines I work on have them to detect material in the vise of an automatic saw.

 

[mike93lx]

My two post lift has a hinged limit bar and a microswitch to cut power.

Don’t they all have something similar?

But that will only deal with the height of the carriage, right? I am guessing the OP wants to limit based upon the roof height of the vehicle so he doesn't hit the cross bar or building.

 

[mike93lx]

An alarm may be worth considering so you don't have to mess with the lift's wiring. Set it to go off maybe 3" from the limit, which would give you time to react. You can also mark your lift posts at the various limits of each of your cars.

Something like a parking alarm might work. One of the grenn/yellow/red light deals

 

[BillK]

But that will only deal with the height of the carriage, right? I am guessing the OP wants to limit based upon the roof height of the vehicle so he doesn't hit the cross bar or building.

No, There is a padded bar that goes across the top and if the vehicle hits it it stops the lift. Had one on the lift in my first shop. Pretty simple and bulletproof.

 

[matt_i]

Depends on how knowledgeable you are with AC/DC circuits. It's going to be difficult for someone to explain to you how to do it without knowing the exact internal wiring of your lift.

Could probably adapt something like this in combination with a relay-
https://www.amazon.com/dp/B001LFPB0M/?tag=atomicindus08-20

That part linked could be wired for 240vac operation per the specs provided, but it could never support the output current to run the motor. In other words it can't be wired in series with the motor. It needs a helper to do the heavy lifting so to speak of AC current. That would get you into a relay or contactor.

Essentially the photoeye contact has to hold the magnetic coil of the relay energized which takes milliamps. The relay contact is holding closed, and wired in series with the motor. If the beam is broken, the relay coil is de-energized, the relay contact goes open and the motor stops and can't be restarted unless the beam is restored.

I can give you a diagram but not currently as more pressing obligations than posting on GJ are calling

 

[mike93lx]

No, There is a padded bar that goes across the top and if the vehicle hits it it stops the lift. Had one on the lift in my first shop. Pretty simple and bulletproof.

Ah, interesting, thanks.

 

[MSPoirier]

Just keep in mind if the hood is open when you lift the vehicle it may be higher then the roof and not engage the stop. This is the only issue with my two post lift. Good luck

- Sam

New England Region

 

[brownbagg]

i painted a line on my up right, not to go above, Its six inch below the limited

 

[Viper98912]

It also depends on what car you have on the lift - some are taller than others, so unless you plan on using that photoeye to detect the TOP of the car...

For me, I put some tape and sharpie on my personal lift that has the car model with an arrow and the word "<---Max"

 

[rlitman]

I've seen safety systems that use a wire strung across the bay just off the ceiling. Press on the wire, and it triggers the safety switch.

 

[jsimon77]

This is all really helpful!

Thanks

 

[rlitman]

I've seen safety systems that use a wire strung across the bay just off the ceiling. Press on the wire, and it triggers the safety switch.

Here's a plan:
String a clothes line from front to back a couple of inches from the ceiling (clothes lines don't really stretch, and are plastic coated, so they won't scratch). Attach it to one wall, and attach it to a pulley at the opposite wall, running down. To that, hang a weight to keep the line under tension so it hangs pretty straight. 10 lbs or so should do.

Attach a snap action lever switch to the wall so that the weight presses it down.

Then wire that switch in series with the lift's high-limit stop switch.

Anything that contacts the line will lift the weight off the switch, breaking the high-limit safety cutoff, instantly stopping the upward motion. It should still allow it to go down under control however.

 

[firebirdparts]

That's a great idea. I could use one of those on the garage door to indicate it's open (and kill the lift). If the door is open, some vehicles would hit it and some (most) wouldn't. The geometry for me is a little complicated.

 

[matt_i]

Here's a plan:
String a clothes line from front to back a couple of inches from the ceiling (clothes lines don't really stretch, and are plastic coated, so they won't scratch). Attach it to one wall, and attach it to a pulley at the opposite wall, running down. To that, hang a weight to keep the line under tension so it hangs pretty straight. 10 lbs or so should do.

Attach a snap action lever switch to the wall so that the weight presses it down.

Then wire that switch in series with the lift's high-limit stop switch.

Anything that contacts the line will lift the weight off the switch, breaking the high-limit safety cutoff, instantly stopping the upward motion. It should still allow it to go down under control however.

This is also a good idea but there's a couple details to also consider. The limit switch pictured is rated for 0.25A @ 240vac. The one lift I've been involved with has an el-cheapo contact that is pulled open by a cable strung across the top. It does however have enough ampacity to handle the 2-3hp motor current which is somewhere in the 6-9A range steady-state.

That switch would also have to be wired to a relay or contactor which could handle the motor amperage. A person would also have to consider how to enclose the switch properly if it were wired for 240vac.

This is how I would wire the photoeye (P.E.) or the limit switch pictured above. I probably have the ANSI symbology wrong for the maintained high-limit which uses a cable to pull it open if the vehicle gets that high.

Case 1 is the basic lift wiring.

Case 2 is with the relay integrated. The -] [- is a normally open contact of the relay. The -0- is the coil of the relay. The number 40 is just a generic number to show that they are connected without drawing that relationship graphically. CR is just Control Relay.

Case 3 is how things look if the switches make and break both poles of the 240vac. Its possible for safety reasons that its wired like that. I can't recall now the way the one I worked on was setup.

 

[rlitman]

That's a great idea. I could use one of those on the garage door to indicate it's open (and kill the lift). If the door is open, some vehicles would hit it and some (most) wouldn't. The geometry for me is a little complicated.

Maybe, but if you want to see if the garage door is open, I'd use an alarm contact that breaks the moment the door is anything other than fully closed.

Simply testing that the door is fully open doesn't prevent one from opening the door while the lift is up. Also, while a GDO has limit switches, putting two similar limit switches in parallel (your is the second, to sense the door), may not reliably activate the second switch, since the open door position may vary by more than the movement of the lever.

Then again, that will prevent any use of the lift with the door open, which may not be what you want. Plus you probably want to prevent the door from opening with the lift up.

Maybe something with a light beam and two reflectors could be made to stop the lift at one height with the door up, and allow a higher lifting with the door down. It might take some thinking.

This is also a good idea but there's a couple details to also consider. The limit switch pictured is rated for 0.25A @ 240vac. The one lift I've been involved with has an el-cheapo contact that is pulled open by a cable strung across the top. It does however have enough ampacity to handle the 2-3hp motor current which is somewhere in the 6-9A range steady-state.

That switch would also have to be wired to a relay or contactor which could handle the motor amperage. A person would also have to consider how to enclose the switch properly if it were wired for 240vac....

100% agreed. I made the [poor] assumption that the upper limit switch is on a 24V control circuit, and that neither the switch nor its wiring sees full motor current. While it might be possible to switch motor current directly with such an arrangement, I would strongly advise against it.

If the lift in question has it's own control circuit and contactor, all the better. If not, you could wire your own with a contactor, but there are easier options as well, such as relays with built in transformers (often made for furnaces or built-in-vacuums and such).

Just be aware that not all packaged relays will work for this purpose. In a different project, I used a Functional Devices RIB01SBCDC, which has low voltage "dry contact" input that at first glance would appear perfect for this. However, it suffers from a delay of several seconds after making or breaking contact to the change of state, and with a moving device like a lift, that delay is unacceptable.

 

[hotrod1968]

My two lifts two pole lifts ( different brands) have a padded bar. In my opinion if one is not observant enough to not keep from running ones rig into the limit bar, ceilings whatever I would question his ability to work safely under the lift. The biggest safety factor in play is you.

Sent from my SM-G965U using Tapatalk