Mohawk lift pics and issues

[jdav7]

Hi,

Here are some photos of a Mohawk lift I installed in my garage. Larger pics and some more photos can be found here:

http://www.maj.com/cgi-bin/gallery.cgi?f=151868

I would like to thank OldCarGuy for answering the questions I had when deciding to purchase a lift.

I covered the hydraulic lines with some plastic gutter from Lowes to give the install a cleaner look on the ceiling. I also cut some floor matts down and store them on the trollies. It keeps them handy for my knees when placing the pads under the vehicle and also keeps the doors from hitting the trolley. Running 120v outlets to the posts was the best thing I have done in the garage. No more running extension cords from the wall.

I must say I am glad I bought it, but I would recommend getting it through a distributor instead of direct from Mohawk. I have tried four times to get a decal to replace the damaged one, and after many promises to send one, I still have not seen it.

I am also having an intermittent issue where the hydraulic pump will sound funny and the motor will pull four times the normal current when raising. They said the problem was probably a bad winding in the motor. A new motor was sent and I replaced it, but it has not fixed the problem. It has been over a week now, and the other motor is waiting for them to get a call tag for UPS to ship it back.

I think I will have to resort to making a .wav or .mp3 of the motor running in this condition and send it to them and Monarch, who makes the power pack, to get someone to identify what the problem is.

Joe

 

[Tscott]

I have never come across a motor that had an "intermittent" bad winding. I seriously doubt that is even possible. A bad winding is just bad. However, some signs of a bad winding are if the motor run backward or if it stops in a certain position, on the next start, the motor will freeze and just sit in the same spot. Just for your protection, I would double check the voltage to the motor and the name plate on the motor. Anything other than that will be their problem, and I would not mess with it.

Either way, nice lift and congrats, but admit it, you will miss the feel of good old cardboard on you back.

Tom

 

[bmwpower]

I'm not completely familiar with the Mohawk lifts, but on my Rotary it took a little while to get over the initial wear-in period. The Rotary units have these teflon pads that ride up and down the column. Initially, the unit was kind of jerky. After some use, things wore in and it's working as it should now. I didn't check the amperage the unit was pulling, but I would imagine it would have been more than normal, but not excessive.

Are the hydraulic lines all in good condition and not bent/crushed?

Just thinking off the top of my head....

 

[PxTx]

Do they use a relay, or does one leg pass directly thorugh the switch? I would suspect the probelm you are describing is a deteriorated point contact either in a contactor or in the actual switch you use to raise the lift.

I've seen brand new switched (which were underrated) act just as you described.

 

[OldCarGuy]

It’s too bad that Mohawk has been slow to respond to your needs and concerns. That was totally opposite of my personal experience with them. Though I worked through the sales manager with questions about installation. He directly addressed my issues or quickly passed on answers that he received from their engineers. Once he was at a trade show, and I was turned over to their top executive. The next day I received two sets of decals that I asked for. I just wanted them for appearance sake…

The motor on my Mohawk lift doesn’t even get warm with continual use. So I’m sure that you have some kind of issue to deal with. If you replaced the hydraulic unit’s motor, and it still overheats. Most likely the motor wasn’t the problem. I would first rule out a bad breaker, loose connector wire or connection. Then I would put a volt meter and amp probe on the motor’s leads. To see if there is an unusually high Voltage drop and big increase in Amp draw, when the motor makes that noise you talk about.

The carriage does not ride on plastic glides like most other units on the market. They use a series of eight heavy-duty roller bearing similar to a lift truck mast. However if they were seriously binding, it would put an undo load of the hydraulic system. Though I wouldn’t think that could happen. To check for binding, disconnect the cylinders to see how freely the carriage moves.

Next I would look at the hydraulic system. Mainly the pressure relief valve and pump. To see if there are any erratic problems. You would need to install a pressure gage to analyze the system. I would think that Mohawk would guide you through all this.

 

[bmwpower]

Don't Mohawk units come with onsite warranty? My Rotary does.

 

[ron in sc]

Here are some photos of a Mohawk lift I installed in my garage.

My top choices are the Mohawk A7 or a Rotary Lift. Based on my research I think I could get better service from the Rotary people because they sell so many and have local people that service them. I am kind of partial to the Mohawk for a lot of reasons. If I get the Mohawk it would be from the distributor nearest me, still out of state though.

Did you install lift yourself and is it an A7?

 

[jdav7]

Hi,

The model# is System1A-10. The serial number is A7E145.

Joe

 

[jdav7]

Do they use a relay, or does one leg pass directly thorugh the switch? I would suspect the probelm you are describing is a deteriorated point contact either in a contactor or in the actual switch you use to raise the lift.

I've seen brand new switched (which were underrated) act just as you described.

It goes through a double pole pushbutton switch. The only reason I would rule out a bad switch or breaker would be that the current goes up when this happens. Normally about 14Amps to over 60Amps. Voltage at the motor is 240V. It drops a couple of volts when running normally. It drops to 225V when running the high current. 60A over 50' of 10ga should drop some volts, so I don't think the electrical supply is the problem, but I could be wrong...

 

[jdav7]

Here are pics of the motor current in both normal and the high current condition. I also recorded wav and mp3 files of the noise the lift makes. Too bad I cannot attach the sound files in this forum. I'm going to send them to Mohawk today to see if they know what it is.

Joe

It’s too bad that Mohawk has been slow to respond to your needs and concerns. That was totally opposite of my personal experience with them. Though I worked through the sales manager with questions about installation. He directly addressed my issues or quickly passed on answers that he received from their engineers. Once he was at a trade show, and I was turned over to their top executive. The next day I received two sets of decals that I asked for. I just wanted them for appearance sake…

The motor on my Mohawk lift doesn’t even get warm with continual use. So I’m sure that you have some kind of issue to deal with. If you replaced the hydraulic unit’s motor, and it still overheats. Most likely the motor wasn’t the problem. I would first rule out a bad breaker, loose connector wire or connection. Then I would put a volt meter and amp probe on the motor’s leads. To see if there is an unusually high Voltage drop and big increase in Amp draw, when the motor makes that noise you talk about.

The carriage does not ride on plastic glides like most other units on the market. They use a series of eight heavy-duty roller bearing similar to a lift truck mast. However if they were seriously binding, it would put an undo load of the hydraulic system. Though I wouldn’t think that could happen. To check for binding, disconnect the cylinders to see how freely the carriage moves.

Next I would look at the hydraulic system. Mainly the pressure relief valve and pump. To see if there are any erratic problems. You would need to install a pressure gage to analyze the system. I would think that Mohawk would guide you through all this.

 

[jdav7]

The crazy thing is that it is itermittent. It will work fine several times and then one time make this noise. Releasing the button and pressing it again may make it sound fine again. Or I may press it several times and it does not come out of it. It does not matter what height it is at or if it is loaded with a vehicle or not.

I'm not completely familiar with the Mohawk lifts, but on my Rotary it took a little while to get over the initial wear-in period. The Rotary units have these teflon pads that ride up and down the column. Initially, the unit was kind of jerky. After some use, things wore in and it's working as it should now. I didn't check the amperage the unit was pulling, but I would imagine it would have been more than normal, but not excessive.

Are the hydraulic lines all in good condition and not bent/crushed?

Just thinking off the top of my head....

 

[Tscott]

Well, lets look at this logically. We know that the resistance in the motor circuit is dropping some how. So it could be an intermittent short in the wiring to and from the motor, not likely, most shorts of this nature are permanent and would normally kill the breaker.

This leaves the motor, which you have changed. So possibly the motors are suffering from the same problem, not very likely but still possible.

Or something is slowing the motor, causing a higher than normal load therefore slowing the rotor and causing a high amp condition. I would say this is the most likely situation, maybe you could try and run the motor you pulled out of the lift free of load. Not sure how long you usually run the lift before the problem occurs but if you can run the extra motor then maybe you can prove that is not the problem.

Also something else I noticed, that may be nothing is the sin wave on your multi meter. It looks like the wave has decreased in frequency as the load increases, not sure if you are just zoomed in or if the frequency is actually dropping. Not sure of what that means, or if it means anything at all.

Anyways I would try and ensure there is nothing slowing the motor in any way and then test the motors free from load to try and eliminate that variable. Hope this helps, but judging by your multi meter, I would say you probably know what you are doing.

Tom

 

[OldCarGuy]

It goes through a double pole pushbutton switch. The only reason I would rule out a bad switch or breaker would be that the current goes up when this happens. Normally about 14Amps to over 60Amps. Voltage at the motor is 240V. It drops a couple of volts when running normally. It drops to 225V when running the high current. 60A over 50' of 10ga should drop some volts, so I don't think the electrical supply is the problem, but I could be wrong...

At this point, this has become way over my head. But what size breaker do you have? And if the wire size is #10 gage, it's rated at only 30 Amps.

The motor on my Mohawk is a 2 1/2 HP Boldar rated at 13 Amp @ 230 Volt, and 13.7 Amp @ 208 Volt. And draws about 10 Amps under load.

I'd like to hear what the Mohawk crew has to say about this..

 

[W-Cummins]

Also something else I noticed, that may be nothing is the sin wave on your multi meter. It looks like the wave has decreased in frequency as the load increases, not sure if you are just zoomed in or if the frequency is actually dropping. Not sure of what that means, or if it means anything at all.
Tom

The Frequency did not change looks like the sampling rate did, from 20ms to 10ms



What is the resistance across the windings do you have a meger to test it?


William....

 

[bmwpower]

The Frequency did not change looks like the sampling rate did, from 20ms to 10ms

I'm wondering if the hydraulics are the cause. How does the lift balance the 2 sides do they use a geared flow divider like a press brake or....

William....

Yea, could you slap a gauge on the system to see if it's building pressure? All it would take would be for something to be floating around in the system to give you sporatic problems.

 

[jdav7]

It has a 30A breaker at the panel. I have not ran it long enough (4-5sec max) in this condition to trip the breaker.

From your motor specs, it sounds like the same motors that I have tried.

I talked to Buck at Mohawk today. He had been on vacation, and the other service guy was swamped because of his absence. I guess that was the reason for the slow response. They got my sound files, but I have not heard an exact diagnosis from them yet. Hopefully, they can tell what would be wrong from listening to them. Anyway, he is sending a replacement power pack (motor, pump, and tank) for me to swap out.

Joe

At this point, this has become way over my head. But what size breaker do you have? And if the wire size is #10 gage, it's rated at only 30 Amps.

The motor on my Mohawk is a 2 1/2 HP Boldar rated at 13 Amp @ 230 Volt, and 13.7 Amp @ 208 Volt. And draws about 10 Amps under load.

I'd like to hear what the Mohawk crew has to say about this..

 

[jdav7]

That's what I thought at first. But the intake is supposed to have a filter on it in the resivoir. Maybe they left it off???

I got a pressure gauge on it that has a scale in pounds so you can see how much weight it is lifting. The gauge reads the same 6000-6200 lbs when it is running up with my truck on it, either running normally or when making the nasty noise.

I thought maybe they would say that I still had air in the system or something simple to fix after listening to the sound files. But, they are just sending a complete power unit for me to swap out. We'll see...

Joe

Yea, could you slap a gauge on the system to see if it's building pressure? All it would take would be for something to be floating around in the system to give you sporatic problems.

 

[jdav7]

Good call. I did change the sampling rate between the two current measurements.

I hadn't measured the resistance yet, but they are now sending a complete hydraulic unit to change out.

Joe

The Frequency did not change looks like the sampling rate did, from 20ms to 10ms



What is the resistance across the windings do you have a meger to test it?


William....

 

[ron in sc]

Joe,
Did you buy your lift from a Mohawk distributor? I was thinking that he would be the one to help you get your problems resolved since he probably had his authorized installer set it up.

 

[krooser]

Mohawk is probably the best built lift on the market today...congrats on buying a safe lift.

 

[jdav7]

I bought it from the factory and installed it myself.

I did get the replacement power pack in. I'll be swapping it out this weekend.

Joe

Joe,
Did you buy your lift from a Mohawk distributor? I was thinking that he would be the one to help you get your problems resolved since he probably had his authorized installer set it up.

 

[zr1nsx]

I briefly read through some of the posts to this subject. I have a Worth 4post lift and when I initially installed it, it had similar symptoms. My lift has a capacitor start motor on it. It has a centrifugal switch mechanism on the internal motor shaft with weights on it. When you first start the motor and before it gets up to speed, the current runs through a capacitor. When the motor gets up to speed, the weights sling upwards disengaging the starting circuit running through the capacitor. On my lift, the centrifigal mechanism was binding, thus not allowing the motor to come off of the starting circuit. Being a Tool & Die maker with a nicely equipped shop, and getting no support from the lift manufacturer, I disassembled the motor and rebuilt the centrifugal starting switch. It had a part that was apparantly not within the design tolerance which was causing the assembly to bind. When the motor won't come off of the starting circuit, it will draw a boat load of current. Has worked fine for years. By the way, the motor was a Chinese Leeson motor. I called the lift manufacturer to let them know what I had found, because I figured they had many of these motor/pump assemblies that would be causing problems in the field. They weren't the slightest bit interested in what I had to say.

I know very little about electrical motors or how the circuitry works. My brother however is president of a very large motor winder in the Indianapolis area. With his knowledge and my mechanical skills, we were able to correct the problem. The motor did blow a couple of capacitors before we figured out exactly what the problem was however.