More forklift load calculation fun...just one truck this time..
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  1. #1
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    Default More forklift load calculation fun...just one truck this time..

    Any idea why the rated capacity of forklifts often don't follow the math one might expect ? In below example the rating at 24" is 24,300 so for 36" load center one might expect 24/36= .666 x 24300= 16,200...rather than 19,400.

    This is not just a Versa-Lift thing as I've noticed the same ratings on other trucks such as Hoist and Royal, where the 30 and 24 inch load center figures stamped on their data plates are not what I would expect.

    Versa-Lift - Model 25/35

    I'm curious as I just bought a Royal Liftmaster rated at 22,000 lb at 30 inch load center and wondering what it would have been rated at the more industry standard 24 inches ? The math (22000 x 30 divided by 24) would say 27,500 lbs....but I wonder... suspect the answer has something to do with "load moment" calculations but you tell me.
    Last edited by Milacron; 02-21-2019 at 08:22 AM.

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    I don't exactly have your answer but I am thinking that you need to factor in the distance from the center of the axle. I don't know the specs of your truck but for instance if the forks are 24 inches past the axle center line it would be 48/60 for your first figure instead of 24/36 in my opinion. I may be wrong here but I'm thinking you need to figure in that distance into the equation.

    example 48/60= .8 x 24300= 19440 for 36" center
    48/72= .6667 x 24300= aprox 16200 for 48" center


    Quote Originally Posted by Milacron View Post
    Any idea why the rated capacity of forklifts often don't follow the math one might expect ? In below example the rating at 36" is 24,300 so one might expect 24/36= .666 x 24300= 16,200...rather than 19,400.

    This is not just a Versa-Lift thing as I've noticed the same ratings on other trucks such as Hoist and Royal, where the 30 and 24 inch load center figures stamped on their data plates are not what I would expect.

    Versa-Lift - Model 25/35

    I'm curious as I just bought a Royal Liftmaster rated at 22,000 lb at 30 inch load center and wondering what it would have been rated at the more industry standard 24 inches ? The math (22000 x 30 divided by 24) would say 27,500 lbs....but I wonder... suspect the answer has something to do with "load moment" calculations but you tell me.
    Last edited by jeff76; 02-17-2019 at 08:59 PM. Reason: example change

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    I dont know how accurate this information is.
    Calculate Forklift Attachment Capacity | Cascade


    And this
    Cascade Corporation

    Guidelines may vary with design. They have to where weight distribution is the key factor.

    Tetor totor effect applies

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    Quick math on the Versalift gives me about 23 5/8 to the axle.

    I tried the Cascade calculator on the Versalift chart for the fun of it, and checks out within rounding just like it does with the pencil. I assumed 0 attachment weight and brought every thing back to the fork (0) too to use it for comparing published capacities to each other.

    Milicron, if you measure the axel CL to the fork - measure B in mllud22's Cascade link, you can do the same math you were using, but adding in that measurement to both the multiplication and division as jeff76 indicated.

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    Sooooo, when do we get video of your acquisition getting settled in using your other new acquisition?

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    I suspect your calculations are close to right, when you figure distance from axle. Every Royal I've been around, 24" load center is 44" out from the axle. All Royals are made on the same basic frame, the same frame design that Towmotor designed before Cat bought them. You may have to turn up your pump relief to get it to pick up much over 22k though. It would be best to have a test weight to verify any calculations.

    I've never heard of a Royal lift rated 22k @ 30". What is the model number? Is it a T300 model number?

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    I wanted to change the mast on my forklift some time ago. The forklift guy said that isn't done anymore, but did say part of the rating calculation is the lifts ability to stop with weight at max lift without tipping forward. Granted mine was a 4000 lb baby compared to yours.

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    I bet you’re right on the load moment being a factor, and lateral and dynamic stability. A manufacturer’s engineering department should be able to point to the CFR that defines ratings, and your dealer should be able to get you that if they’re worth a sht and at least the right phone contact if not.

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    center of gravity and wheel traction to truck and load weight combination.
    .
    even when rear wheel doesnt go airborne its still when lightly loaded hard to steer especially with extra weight. i usually worry more about less steering control and uneven floor. over steering or rear going farther than expected is common collision spot with back side of truck hitting wall. sure you can drag load on floor for more steering ability but it leaves a scraping mark on the floor

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    Quote Originally Posted by m16ty View Post
    I've never heard of a Royal lift rated 22k @ 30". What is the model number? Is it a T300 model number?
    20180626_095717.jpg Truck was shipped today....noticed in photos for the first time it has 5 valves/levers...turns out the fork positioning will move each fork separately, rather than the usual single lever "both= toward each other, both= away" action..thus the extra lever....very cool.

    Further mystery is how it could be rated only 1,000 lb less capacity when including the side shift fork positioning attachment at 36 inch centers ...whereas somehow it is rated at 22,000 at 30" centers presumably with no attachment.

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    It's based on the moment about the front axle, so force/weight (mass times gravity) times distance, and I'm sure there is also a fair safety factor in those numbers.

    Moving individual forks would be really handy.

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    Quote Originally Posted by Milacron View Post
    Further mystery is how it could be rated only 1,000 lb less capacity when including the side shift fork positioning attachment at 36 inch centers ...whereas somehow it is rated at 22,000 at 30" centers presumably with no attachment.
    A guess, but the first "Equipped With" number could be a heavy duty counter weight.

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    Quote Originally Posted by OldParts View Post
    A guess, but the first "Equipped With" number could be a heavy duty counter weight.
    Interesting thought..."CWT" indeed... if true, another bonus I didn't expect as that might make this forklift equivalent to aprox 28,000 lb capacity at the usual 24" load center rating. The seller did mention that in the past, with a little extra temporary counterweight, they picked up 30,000 lb with this truck like it was nothing.

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    Quote Originally Posted by Milacron View Post
    Any idea why the rated capacity of forklifts often don't follow the math one might expect ? In below example the rating at 36" is 24,300 so one might expect 24/36= .666 x 24300= 16,200...rather than 19,400....
    Don't you have that backwards? Isn't the capacity MORE at 24" than at 36"?

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    Just equalize the moments.

    So, assuming the center of the front axle is 16" behind the forks, the total moment is 22,000lbs*(30"+16") = 1012000ft-lbs.

    Then back out the number for 24". 1012000ft-lbs/(24"+16") = 25,300lbs.

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    Quote Originally Posted by Milacron View Post
    20180626_095717.jpg Truck was shipped today....noticed in photos for the first time it has 5 valves/levers...turns out the fork positioning will move each fork separately, rather than the usual single lever "both= toward each other, both= away" action..thus the extra lever....very cool.

    Further mystery is how it could be rated only 1,000 lb less capacity when including the side shift fork positioning attachment at 36 inch centers ...whereas somehow it is rated at 22,000 at 30" centers presumably with no attachment.
    I’m not familiar with the TA series. We have several of the T series. Wonder what the difference is in the TA vs the T series, A quick google search shows they both look pretty much the same.

    It’s worth noting that Royal has been bought out by Nordco. I talked to them a year or so back about a new Rig-N-Lift. Their core business is railroad equipment, and they seemed clueless about forklifts. At the time I called them, I got the impression that they hadn’t even built any lifts at that time, but was open to the idea if I agreed to buy one. All that being said, I wonder what the future parts availability will be.

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    Quote Originally Posted by awander View Post
    Don't you have that backwards? Isn't the capacity MORE at 24" than at 36"?
    Right...sorry, got figures mixed up...corrected just now.

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    Quote Originally Posted by m16ty View Post
    I’m not familiar with the TA series. We have several of the T series. Wonder what the difference is in the TA vs the T series, A quick google search shows they both look pretty much the same.
    According to my observations looking at eLiftruck.com and eBay ads, the T series seem to go from 16k to 100K in capacity, whereas the TA series is limited to 25K capacity. Perhaps the TA trucks are slightly narrower width overall and shorter wheelbase ?

    Re Nordco, apparently they have made at least 1....

    2018 LP Gas Royal RNL30/40B Cushion Tire 4 Wheel Sit Down (Indoor Warehouse)

    Interesting the stackable counterweight setup... probably for trucking purposes where due to extreme weight the forklift has to be shipped on one truck and the weights on another.



    I thought this a new design but apparently Royal made the "Rig-N-Lift" version before the sell out as I see some yellow ones when Googling 'Rig-N-Lift' images. The "30/40" model number would indicate this one probably has extendable rear.


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    Quote Originally Posted by Milacron View Post
    According to my observations looking at eLiftruck.com and eBay ads, the T series seem to go from 16k to 100K in capacity, whereas the TA series is limited to 25K capacity. Perhaps the TA trucks are slightly narrower width overall and shorter wheelbase ?

    Re Nordco, apparently they have made at least 1....

    2018 LP Gas Royal RNL30/40B Cushion Tire 4 Wheel Sit Down (Indoor Warehouse)

    Interesting the stackable counterweight setup...


    Royal had a good website, with lots of info on all their models. Only thing Nordco has on their website is some vague general discriptions and some stock photos of the old Royal lifts. When talking to them, I just got the impression that they weren’t really interested, which begs the question, why did they buy Royal if they weren’t going to pursue the heavy lift truck market?

    Honestly, in the heavy lift truck market, it’s hard to compete with the likes of Versalift and Hoist. Nordco/Royal and Landoll have some nice designs, but are priced about the same as Versalift.

    I’ve crawled all over a late model Royal Rig-N-Lift. They are the same old Towmotor frame design, all they did was add some extra tubing on the outside of the frame to facilitate the extendable counterweight, and redesign the rear counterweight section to accept stackable weights. First it was Towmotor, Cat bought Towmotor, at first Royal went into a licensing agreement with Cat to build lifts, then Royal bought the big lift division outright, and Nordco bought Royal. Still the same basic design from the beginning.

    What engine does yours have in it? All our old Cat T series have IH engines, the later model Royals have Chrysler v8.

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    Quote Originally Posted by m16ty View Post
    What engine does yours have in it? All our old Cat T series have IH engines, the later model Royals have Chrysler v8.
    According to seller, GM 4.3 liter V6 Vortec. Maybe that's another difference between T and TA....the TA gets a smaller engine ?

    (on edit) There's another Royal TA on eBay and it also has GM Vortec 6


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