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Pallet Jack Design

03/16/2017 3:23 PM

Hi….I’m an OTR truck driver and use a pallet jack to unload/load trucks on a regular basis. I’m designing my own custom pallet jack that better suits my needs. I’ve attached a pic of a standard pallet jack which has a load capacity of 5500 lbs, lifting a 48”x40 wood pallet. What I’d like to do is replace the formed forks, which are 1/8” thick steel (in the pics), with rectangular A36 flat steel stock. I would like to replace the formed 1/8” thick forks with 5” wide A36 flat stock. My question is; how do I calculate the thickness of the A36 flat stock, with the same load capacity of 5500 lbs lifting a 48 x 40 pallet?

Thanks

Greg

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#1

Re: Pallet Jack Design

03/16/2017 4:05 PM

Go with 2" that way it will fit snugly in the sawn off stubs of the original forks.

Or were you hoping to make them thinner?

I see you've made them a bit narrower: was that the main reason for the re-design.

Two pieces of 2" x 1" ( ║ . ║ ) with a few welded cross members would give you an easy way to fit new wheels.

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#2
In reply to #1

Re: Pallet Jack Design

03/16/2017 4:36 PM

Thanks Randall......and yes my idea is to make the forks thinner. The standard pallet jack in the pics cannot get underneath the pallet from the side cut-outs, because it's too high. For example, sometimes loader's (with a forklift) will turn a pallet sideways, so using a standard pallet jack, you can't get underneath it due to the pallet jack fork height. Consequently, we'll have to hook a chain up to the pallet and drag it out so that you can get underneath it from the front. This is in situations where the customer does not have a dock, so the driver has to tailgate the pallets. My idea is to make the forks thinner, so that I can access the front and sides of the pallet.

Greg

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#4
In reply to #2

Re: Pallet Jack Design

03/16/2017 5:09 PM

For that kind of weight you probably need to go solid.....

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#7
In reply to #4

Re: Pallet Jack Design

03/17/2017 1:37 AM

Going solid is going to get much heavier, very quickly.

Assume each fork starts with two (2) 2" × 1" x 48" solid bars. Without anything else, that is already over 2800 lbs of steel.

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#16
In reply to #7

Re: Pallet Jack Design

03/17/2017 10:47 AM

54.45lbs.

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#29
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Re: Pallet Jack Design

03/17/2017 4:31 PM

Oops. Thank you.

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#28
In reply to #7

Re: Pallet Jack Design

03/17/2017 4:29 PM

Big error here. Thinking numbers for gm/cc but calculated as lbs/in3 . Oops.

198 in3 x 0.284 lbs/ in3. Is a little over 55 lbs.

Sorry about that.

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#3

Re: Pallet Jack Design

03/16/2017 4:56 PM

Where are you going to stash the mechanism that raises/lowers the front wheels?

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#5
In reply to #3

Re: Pallet Jack Design

03/16/2017 5:13 PM

That mechanism will be located underneath the flat stock, in a similar fashion as the standard pallet jack, although with smaller diameter wheels. The max fork height I need to get underneath the pallet from the side is approx. 1 7/8" vs the front of the pallet slots which are aprox 4" in height.

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#9
In reply to #5

Re: Pallet Jack Design

03/17/2017 7:11 AM

You are going to need pretty much every bit of that 1.875" (or 1.75" to leave a little room to slide under) to support loads up to 5500 lbs.

It isn't really the thickness of the material on the forks so much as the thickness of the entire fork ( the 2.75" dimension in you picture) that corresponds with supporting the load. Some minimum thickness it required on the face of the fork but that isn't what is most critical for the load.

You really can't have the wheels using up part of the 1.875" left for the beam, so the wheels need to retract into the beam space or between two tunes that form one fork. On the very front of the fork might be another option though you might want the front wheels not so far out so that the beam doesn't have to be so long.

If I were doing this, I would look at building each fork using two (2) 1.75" square 0.12 wall 4130 chromolly tubes connected with enough space between for a wheel. The fork wheel shouldn't be too far forward and the rear wheel should be as close to the back of the loads possible. 4130 is reasonably priced, easily tight welded even to other steels. It does need to be painted. 4130 1.75" 0.12 square tubing is readily available as it is used in motorsports and aircraft.

Be careful about using smaller wheels. It may be very difficult to get smaller wheels to function correctly on slightly rough surfaces.

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#13
In reply to #9

Re: Pallet Jack Design

03/17/2017 9:10 AM

Great idea, thank you....gottcha on the smaller wheels consideration.

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#19
In reply to #9

Re: Pallet Jack Design

03/17/2017 12:32 PM

Hey...I was curious as to the method that is used to form the forks on a standard pallet jack (in the pics). Are you familiar with the process to bend .125 steel to get those 90 deg bends? Perhaps "roll forming" or using a press brake ?

Just wondering.

Thanks

Greg

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#26
In reply to #19

Re: Pallet Jack Design

03/17/2017 4:09 PM

There are a lot of ways to shape those pieces. By press would have the advantage of being able to minimize welds...at least keep welds out of the most critical areas. That will remove any concerns over heat treating or strength reduction in those areas. You could probably form most of both of the forks and body (?) out of one piece.

The key would be finding a decent metal shop near by.

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#27
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Re: Pallet Jack Design

03/17/2017 4:26 PM

Thanks.

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#6

Re: Pallet Jack Design

03/16/2017 7:39 PM
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#8

Re: Pallet Jack Design

03/17/2017 5:14 AM

I would have thought that the existing forks get their strength from the formed shape, the side walls giving them stiffness. As a starting point, I would look at the flat forks on a fork lift truck.

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#10

Re: Pallet Jack Design

03/17/2017 7:59 AM
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#12
In reply to #10

Re: Pallet Jack Design

03/17/2017 8:42 AM

Interesting that the increase of 1500 lbs load capacity from 4000 lbs to 5500 lbs adds at least $645 to retail, almost tripling the price.

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#15
In reply to #12

Re: Pallet Jack Design

03/17/2017 9:25 AM

Ya...they are a bit pricy.

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#17
In reply to #10

Re: Pallet Jack Design

03/17/2017 10:58 AM

The one in the first link apparently is only good to 4800 lbs.

Second link OK on weight to lift.

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#11

Re: Pallet Jack Design

03/17/2017 8:15 AM
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#14
In reply to #11

Re: Pallet Jack Design

03/17/2017 9:15 AM

Yes.....I realize you can buy one. Just want to do it myself. Thanks.

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#18
In reply to #11

Re: Pallet Jack Design

03/17/2017 10:59 AM

That one does not meet weight class specification, missing by a mere 500 lbs.

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#20

Re: Pallet Jack Design

03/17/2017 1:25 PM

In replacing the formed forks with flat bar you will still need to mill a good bit of the under side away for the push bar that lifts the wheels. So the thinner you make the forks the thinner the push rod. In order for the push rod be able to handle the same force it will need to be wider.

Worked on pallet trucks many years ago. Most manufacture make a low profile jack. About 1 3/4" Height.

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#21
In reply to #20

Re: Pallet Jack Design

03/17/2017 1:33 PM

Thanks for the info.....just curious, how do they form those forks on a pallet jack? Do they maybe use "form-rolling" or maybe a press brake to get those 90 deg bends on .125 steel?

Thanks

Greg

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#22
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Re: Pallet Jack Design

03/17/2017 2:44 PM
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#24
In reply to #22

Re: Pallet Jack Design

03/17/2017 2:58 PM

That's interesting...thanks.....from the video, it looks like the forks are pressed in a mold....didn't think of that.

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#23

Re: Pallet Jack Design

03/17/2017 2:58 PM

It would be much cheaper to find a used one locally and modify it to spec....

http://www.ebay.com/bhp/pallet-jack

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#25
In reply to #23

Re: Pallet Jack Design

03/17/2017 3:06 PM

But when you start messing with it, there goes the lift weight safety rating! Right out the window.

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#31
In reply to #25

Re: Pallet Jack Design

03/17/2017 8:43 PM

I'm a bandido....hehe

Quick hide the jack....

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#34
In reply to #31

Re: Pallet Jack Design

03/20/2017 10:46 AM

What a cute little sweety! Children are certainly a source of joy in the world!

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#30

Re: Pallet Jack Design

03/17/2017 4:50 PM

Thank you everyone for your input. I have a good idea what to do.

Thanks

Greg

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#32
In reply to #30

Re: Pallet Jack Design

03/18/2017 7:02 AM

Thanks for staying "engaged", and, giving us some closure Greg: you have no idea how many people come here and ask a question without nearly enough information, and often including acronyms that only about 5 people on the planet know; and then disappear leaving us high and dry just guessing.

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#33
In reply to #32

Re: Pallet Jack Design

03/18/2017 7:55 AM

You bet....thanks again.

Greg

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#35

Re: Pallet Jack Design

04/10/2017 4:33 AM

The whole point of the thickness of the current fork is to accommodate the forward lifting wheel assembly. If you wish to make it a lower profile then you'll need to devise a very low profile wheel and linkage for forward lift. That said tubing is stronger than solid bar steel and will leave you the space for linkage and rollers.

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