We are checking the stresses in granite pavers, for when a forklift truck goes over them. We are having trouble finding the following information. We want to lift a 3300 pound load.
- assuming that we get a forklift with pneumatic tires, to what pressure are the tires inflated, generally?
- if we get a forklift with solid tires, how can we determine the contact area of the rubber with the pavement. We cannot contact the tire manufacturer because the contractor does not know which tires will be on the forklift that he rents for the particular project
- with pneumatic tires, is there any safety issue to reducing the tire inflation pressure about 25% so that we get a bigger tire contact area with the pavement (and therefore less flexural stress in the paver when analyzed with the Westergaard equations).
-is there any manufacturer that publishes either the centre of gravity of the unloaded unit (i.e. with no load being lifted) OR the front and rear axle loads of the unloaded unit
Showing items 1 - 7 of 7 results.
If I were in your position I would do the following:
1) I would rent from a local forklift dealer rather than a rental yard- rate might be higher, but you can specify exactly what you need
2) The forklift dealer can give you the exact specifications on weight distribution at different levels of weight carrying.
3) Given the specifications, you can from there figure out the weight per inch of contact area.
A pnuematic style tire (air or solid pnuematic) has more contact area than a solid press on tire.
A lighter capacity lift will have more loading on the drive tires than a heavier capacity life- at 3500 lbs.
You definitely cant use cushion tires outdoors. Lowering the pressure on pneumatic tires will cause damage and instability. Also, low tires tend to scrub and twist as they roll, making things worse. There are soft compound tires with no lugs, that are slip resistant in wet conditions. We use them on Tennant scrubbers. Soft wide footprint, but dont last long.
To protect floors, use plywood. We drove a 10,000 lb Reach truck through a Museum in Ottawa that had beautiful marble floors!
thick plywood was laid down as the truck moved through sensitive areas.
Forklifts with Cushion Tyres are best for granite pavers. Press-on's tires are a strict no-no for any outdoors, particularly with uneven floors. Ask Forklift suppliers to offer forklift with 3-Layer or 3-Compound Solid Cushion tyres, for increased suspension. No Forklift rental co. will agree to lessen the inflation pressure, especially if you are a causal customer.
Just for the record, a close approximation of the tires foot prind loading of an air filled pneumatic tire is teh inflation pressure of the tires.
Secondly, theoretically and something to think about, a 125 lb woman wearing a pair of 7" spiked heel pumps can exceed the maximum floor loading of most buildings or run ways at a gentlemens clubs. Those heels have less than 1/2" square area of contact surface. So don't ever put your hand on the run way to pick up that dollar bill you just dropped.
Michelin do an industrial tyre over here that is inflated to 135 > 140 psi. Best way to ensure no damage to pavement is to cover it with boarding and avoid contact totally
1. with press-on solids, the tire manfunfacturer can give you foot print area of either standard compound, or non marking compounds which are ~15% softer than std. black compound tires. You will need to provide axle ratings with & with outloads. The drive tires see a higher loadign with a load adn teh steer tires w/o a load.
2. There are some pneumatic (air style vs solid molded) tires - that will go as high as 125 psi in pneuamtic (like single wide profile tires). Most out door truck are soldi with solid molded ( no flats & a 125 psi air line can be difficult to find) - some odl plants have 80 psi in plant air lines for safety concerns.
3. Vehicle CG and axle loadings, if published & not so many do any more - Hyster was the only make that used to give CG location on their lifts but that was long ago) are generally with a standard unit, two stage mast & 42" std. forks and these specs will vary from make to make (all lift trucks are not alike, unlike what some ladies say about men). The sales rep will need to get in contact with the factory to get the info & this may take some, especially if it is not a current production unit it may take some time, as the "engineers (design type no service) aren't too fast to respond & they want "details: too. So be ready w/ make model & s/n & configuration - mast, attachmetents, tire make & size, compund, etc.
This may sound like over kill but as they say "been there & done that" more than just a couple times.
- tire pressure inflation is generally between 90psi to 110psi depending on the mfg of the tire. the tire should have the name of the mfg on it, also the inflation specs, the tire mfg should have all the information of load ratings etc for that tire as long as you have all the information off of the tire so they can identify it for accurate information.
- if you deflate the tire any less than its rated inflation then you risk stability issues. As far as a solid cushion tire there will be no stability issues pertaining to inflation but the tire mfg should also be able to give you rated capacities on that tire as well as long as you have ALL the information off of the tire to give them.
- if you want center of gravity specs for the lift you will have to contact the lift mfg with the model and serial number of the lift in question, their sales reps can get you the standard factory specs on the lift which includes the specs your looking for.
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