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RE: High Tire Pressure on Concrete slab

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Average contact pressure:

1. 30 kN Counterbalance lift truck                        2.4  N/mm2
2. 20 kN Reach Trucl                                          5.6 
N/mm2
3. 20 kN Pallet Truck                                         11.0 
N/mm2

Please include the dynamic multiplication factor 

a. Braking                  1.3
b.cornering                1.4
c. Acceleration           1.1
d. uneven surface       1.2        

If you plan to use Wstergaard equations, please consider fatigue factor
of 2  to withstand an infinite number of  load repetition.

Himat

>>> jkilgore(--nospam--at)leok.com 11/16/2004 1:17:27 PM >>>
I'm not disputing that the tire pressure number is in error (900 is
VERY
high), but tire pressures for earth-moving equipment isn't a good
comparison.  

The tires for equipment designed to run on earth are intentionally
very
large with low pressures and large contact areas to keep from being
buried
in the ground.  Even though the equipment itself is extraordinarily
heavy
(I've climbed on dump trucks capable of carrying 150 tons in addition
to
their own weight, and it was far from the largest piece of equipment
that
Caterpillar makes), the earth pressures are rather low.

High-speed interior equipment will have high pressures and small
contact
areas to minimize tire flexure and friction.

Non-the-less, 900 psi is extremely high.

---
Jason Kilgore
Leigh & O'Kane, LLC
Kansas City, Missouri
________________________________________
From: Padmanabhan Rajendran [mailto:rakamaka(--nospam--at)yahoo.com] 
Sent: Tuesday, November 16, 2004 11:53 AM
To: seaint(--nospam--at)seaint.org 
Subject: Re: High Tire Pressure on Concrete slab

Richard,
 
I suspect that your data is in error.  Find out, from the fork lift
manufacturer, the pressure to which the tires must be inflated. Then
the
contact area will be the load on the wheel divided by the tire
inflation
pressure. In other words, the contact pressure is, theoretically, equal
to
the tire inflation pressure.  
 
For your information, even some of the large Caterpillar earthmoving
equipment have contact pressures less than 50 psi.
 
Rajendran

richard lewis <rlewistx(--nospam--at)juno.com> wrote:
I'm working on the design of a slab for a fork truck that has tire
contact pressure up to 900 psi. This makes for a very small contact
area. The design problem I have for the slab is that the parameters
are
"off the chart" for the PCA design method and the WRI design method.
The
only one that is "on the chart" is the Core of Engineers method
because
it is not based on contact pressure, but axle load and frequency of
traffic.

Are there design standards for the newer fork trucks that high the
high
wheel contact pressure and high speed travel? I have used the text
"Designing Floor Slabs on Grade, 2 ed." by Ringo to check these 3
standards mentioned above. The fork truck manufacturer will not give
me
any direction for slab design. 

Thanks for your help.

Rich

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