Any simple way to accurately measure the traction speed of an electric pallet jack ?

Milacron · Mar 27, 2014

Specifically I need to measure the slow forward speed the pallet jack starts at, and the faster speed it jumps to suddenly when turning the throttle. Ideally with a record of the event electronically, either via direct computer input or taking a video. A small GPS comes to mind but I seriously doubt a GPS would react fast enough.

There may not be a simple (inexpensive) way to do this, but asking just in case anyone has any ideas.

APD · Mar 27, 2014

Tape measure, stop watch, & multiplication.

L Vanice · Mar 27, 2014

If you run it on a floor with standard 12" tiles and take a video with a camera mounted on the pallet looking at the joints in the tiles, the rate of speed could be estimated using a stop watch or the in-camera timer. Or you could take the video of a tape measure laid on any floor. That method is simple, per your request. I can suggest more complex ways to do it, but the equipment list can get a lot more complex than a camera and a tape measure.

Larry

Clive603 · Mar 27, 2014

Quickest and dirtiest method I've used for that sort of thing was a small DC motor wired as a generator driven by a small drum running on the equivalent of the pallet truck tyre. Voltage output rises with speed so some calibration will be needed but it can be pretty linear over a reasonable range. This was maybe 30 plus years back so I hooked it up to a portable, battery powered chart recorder but I imagine there are various inexpensive ways of digital data-logging these days. I imagine same idea would work with the el-cheapo optical RPM thingies if any have a data output.

Around the same era I found (literally, just lying around in the parts drawers) a couple or three CMOS chips which would do the same job very simply if fed from a suitable pulse train (e.g. from an opto-interrupter). Took less than an afternoon to incorporate into a lab device I was building. Presumably something similar can still be got.

Clive

ewlsey · Mar 27, 2014

What about a digital/photo tachometer? Stick a piece of tape on the wheel, then measure the RPM. Pi times the diameter, and you have the speed.

jlevie · Mar 27, 2014

L Vanice said:
If you run it on a floor with standard 12" tiles and take a video with a camera mounted on the pallet looking at the joints in the tiles, the rate of speed could be estimated using a stop watch or the in-camera timer. Or you could take the video of a tape measure laid on any floor. That method is simple, per your request. I can suggest more complex ways to do it, but the equipment list can get a lot more complex than a camera and a tape measure.

This! Video the motion over marks at known distances. Then count the frames from one mark to the next and use the frame rate to calculate the time to cover that distance to get the speed over that segment. A quick trial on floor tiles will tell if the marks need to be further apart. The more frames for a segment the more accurate the results will be.

You will want to use a video editor that tracks frame number and allows stepping by frame for good results.

MetalWOT · Mar 27, 2014

Milacron said:
Specifically I need to measure the slow forward speed the pallet jack starts at, and the faster speed it jumps to suddenly when turning the throttle. Ideally with a record of the event electronically, either via direct computer input or taking a video. A small GPS comes to mind but I seriously doubt a GPS would react fast enough.

There may not be a simple (inexpensive) way to do this, but asking just in case anyone has any ideas.

Don't bother with a GPS. You can't expect them to work in the building reliably. Can you explain what it is that you're trying to do, purpose and give me the criteria you need?

Have someone else operate the equipment. Find an uneven spot somewhere in the parking lot or a crack on the floor. When it makes the first thump, you start the clock. When the front tire goes past you, you stop. If you choose to stand precisely 50 ft from the crack and it takes 15 seconds, it is 3 1/3 feet per second. Have him turn around, go right past you. You start the clock when front tire passes you, then stop when you hear the thump. Take the average of the two. Repeat the process for each speed setting. This method avoids the point of view error from trying to eyeball from an angle and avoids operator distraction of having him operate and time.

If you just need a three level output for safety audits and such that shows elapsed time or real time on x axis and you just want to know off, lo and high its easy. If you need the actual speed at a fast refresh rate (say 3-5 times a second), instantaneous speed and digitized data for analysis for engineering purpose, it is more involved. Does it need to be reported to host wireless in real time and how long of a duration should the on board system be able to hold the log?

What precision do you need? Down to 0.1mph, 0.1 fps, or ??

Gary E · Mar 27, 2014

What about a 50's bike? lots of them had a speedometer on them and all you'd have to do is strap it to a skid and have someone read it as you drive...

What did you do...get a SPEEDING ticket and your trying to come up with some proof for the Judge that this thing cant possibly go that fast?? LOL

MetalWOT · Mar 27, 2014

jlevie said:
This! Video the motion over marks at known distances. Then count the frames from one mark to the next and use the frame rate to calculate the time to cover that distance to get the speed over that segment. A quick trial on floor tiles will tell if the marks need to be further apart. The more frames for a segment the more accurate the results will be.

You will want to use a video editor that tracks frame number and allows stepping by frame for good results.

This can work, but if it is for process management or engineering purposes, he will need digitized data for subsequent handling to perform calculations to get such thing as acceleration, deceleration, incline and load influence, etc. Analog method means labor for someone to go over and put them into computer and it won't be real time. You'll always only get them in batches.

Peter from Holland · Mar 27, 2014

What about a bicycle odometer
Make sure you can set the diameter of the wheel to the right size

Peter from holland

Miguels244 · Mar 27, 2014

One time or data logged over a period?

adama · Mar 27, 2014

Some of the better tachometers have a wheel attachment for measuring conveyor speed, obviously it will need a smooth floor and a passenger to ride said pallet truck holding the contact wheel to the floors surface :-)

technocrat · Mar 27, 2014

jlevie said:
This! Video the motion over marks at known distances. Then count the frames from one mark to the next and use the frame rate to calculate the time to cover that distance to get the speed over that segment. A quick trial on floor tiles will tell if the marks need to be further apart. The more frames for a segment the more accurate the results will be.

You will want to use a video editor that tracks frame number and allows stepping by frame for good results.

The traditional way was polaroid camera on tripod in a dark room with the shutter open and a strobe light with a suitable period - eg 1 second. Gives a multiple exposure picture with easy to scale distance. This would adapt to video camera no problem.

adatesman · Mar 27, 2014

You'll laugh, but Mattel makes a radar gun for Hot Wheels cars that would work just dandy. Basically the same thing as professional units, but much, much lower power to make it kid-safe. Effective range is ~40 feet, which should be enough for what you need. Looks like they're $100 on Amazon and $50 on EBay.

http://www.amazon.com/gp/aw/d/B000EHLB0M

Milacron · Mar 28, 2014

Thanks folks. As it turns out I don't think I need actual numbers. I laid down a 30 foot tape measure on the floor as straight as I could, taped the iPhone in video mode to the pallet jack battery, aimed at the tape measure, and did some trial runs following the tape measure as best I could. That, combined with the sounds from the jack, make it pretty obvious the sudden increase in speed.

On the theory the manuf. will think I'm "gunning" the throttle, I made another video aimed at the throttle handle. Put a temporary witness mark on the handle, turned the throttle as carefully and slowly as humanly possible.... and there, it's even more obvious the sudden increase in speed. In other words, you turn the throttle and the jack moves slowly...turn it more, no increase in speed, still more and all of a sudden the speed doubles. Should be a seamless transition of speeds, but it very much is not. Not, to the point of being a little bit dangerous and downright irritating to use at best.

The purpose of the videos are to show the manuf. just how bad it is. They keep trying to convince me this is "normal" as the computer testing of the potentiometer shows all is fine and they really have no fix.

Chip Chester · Mar 28, 2014

Hopefully you made passes in both directions to account for floor slope, and the BigAssFan headwind...

If you feel like digging into it, actual pots can get areas of discontinuity or dirt, and respond to appropriate cleaning if not hermetically sealed. There also could be a sort of digitizer involved, or a feedback loop sensor misreporting actual speed. Depends on how fancy the control system is.

Chip

Milacron · Mar 28, 2014

Chip Chester said:
Hopefully you made passes in both directions to account for floor slope, and the BigAssFan headwind...

If you feel like digging into it, actual pots can get areas of discontinuity or dirt, and respond to appropriate cleaning if not hermetically sealed. There also could be a sort of digitizer involved, or a feedback loop sensor misreporting actual speed. Depends on how fancy the control system is.

Inside, so there is no slope. As stated, the pot operation shows fine on computer tests. In other words the tech can connect his laptop to the pallet jacks "computer" and see the acceleration curve on his screen as he turns the throttle. When he does that it looks as it should, so they are baffled what is wrong with it... to the point of now proclaiming it is "normal" and ok. :liar:

MetalWOT · Mar 28, 2014

Is it a variable speed or dual/triple speed? When you turn the throttle from stop, do you hear a high pitch sound that ramps in tone or does it just transition?
If you were to start from stop, then ru up the throttle all the way to high in a smooth motion,the person on the pallet should not feel a lurch or shock similar to what you feel when gear shifts in your car if it has a true electronic variable speed control. Lurch is hard to measure so its easier to feel it like that.

Post the make and model just so we know who makes a pallet jack with crap speed control.

Milacron · Mar 28, 2014

MetalWOT said:
Is it a variable speed or dual/triple speed? When you turn the throttle from stop, do you hear a high pitch sound that ramps in tone or does it just transition?
If you were to start from stop, then ru up the throttle all the way to high in a smooth motion,the person on the pallet should not feel a lurch or shock similar to what you feel when gear shifts in your car if it has a true electronic variable speed control. Lurch is hard to measure so its easier to feel it like that.

Post the make and model just so we know who makes a pallet jack with crap speed control.

On the theory that the topic title in this thread was too specialized to interest some folks in the actual pallet jack problem, I started a new thread once I had the videos on Youtube- http://www.practicalmachinist.com/vb/general/electric-pallet-jack-defective-videos-282662/

MetalWOT · Mar 28, 2014

Milacron said:
On the theory that the topic title in this thread was too specialized to interest some folks in the actual pallet jack problem, I started a new thread once I had the videos on Youtube- http://www.practicalmachinist.com/vb/general/electric-pallet-jack-defective-videos-282662/

I have no idea. What you're referring too is called a control response curve. One for a sports car and one for a tank would be different for example. I dunno anything about pallet jack user experience though. I did though respond to your thread with some keywords that industrial people seem to care about and might search under.

Any simple way to accurately measure the traction speed of an electric pallet jack ?

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