Casters for Heavy Load Handling on a bearing of air. The latest on Air Film Technology in the
Material Handling Industry. Replacement Air Casters, Rentals, rigging equipment
and Air Film Systems. Also Wheeled vehicles with omni-directional steering for
handling heavy loads.
Loads on Air"
FLOOR REQUIREMENTS FOR AIR FILM TRANSPORT
“The floor surface is an important part of the Air Bearing system”
REQUIREMENTS FOR AIR BEARING TRANSPORT
In order to reap the full benefits of air bearing transport one must pay attention to the properties of the floor
requirements. A correctly chosen floor surface will pay dividends in terms of low operating cost and easy handling.
An unsuitable floor surface could lead not only to high traction forces due to friction but also to high air consumption and excessive wear of the air bearing. Inclination or undulation ("sloping") of the floor will also increase the required traction power which might call for the use of powered drive units in addition to the Air Bearings.
In order to fully understand the necessity of operating on a proper floor surface, one must understand
How an Air Bearing works.
The floor surface should be airtight as to enable forming of a load-bearing air film between the floor and the load carrier.
The floor surface shall be smooth as to minimize the air consumption and the friction.
The floor surface must be even (without inclinations) so that the load does not glide away because of low friction.
specifications require that the floor surface
be smooth, non-porous and level. A machine troweled, epoxy treated
concrete floor is ideal - however the job should be carefully done without
marks, pits, cracks, flaking or messy painting. Most modern floors in new
plants meet these demands, if not it is normally possible to achieve a
good result through the use of suitable fillers and epoxy paint. The
illustrations (below) display the allowed maximum undulations and
Section through a bearing
showing the pressure chamber and the thin (.005”) air film on which the
load rides. One can easily appreciate why sharp, protruding grains must be
avoided. Cracks or holes in the floor surface will make the pressure disappear.
Due to their elasticity, Air
Casters adjust to minor unevenness. The level differences should,
however, not be more than 2% of the diameter of the air cushion.
Floor Requirements for inclination should be
kept within certain limits for safe handling of the goods. You cannot
escape gravity - it is heavy going uphill and easy downhill.
On a non-airtight surface, the
air caster may loose so much air that the pressure is not adequate for
lifting the load, i.e. to form the load-bearing air film. A normal
concrete floor without surface-treating is porous and let’s the air pass
through. Also airtight floors can contain joints, holes and cracks, which
can easily be filled or covered with tape. It's important to stick to the
floor requirements listed here.
The expansion joints shall be
filled with an elastic composition. The best material is a rubber-like
urethane composition, the shore hardness being approx. 80 in order to be
able to fill the joint properly, a joint width of approx. 3/8” is
recommended. The joint composition can preferably be slightly above the
floor surface. (See illustration, on right)
FILLED EXPANSION JOINTS
It is often necessary to
improve the floor surface with filling composition. Grinding is sometimes
needed for binding the composition to the surface. If one can not maintain
the floor specifications and floor requirements mentioned here. then a new
floor may have to be poured.
The floor smoothness is a
matter of great importance when judging a floor’s suitability for air
bearing transport. Although there are a number of measuring devices
available on the market there is a lack of universal norms. In the last
resort, one is left to make a visual evaluation.
Normally one cannot operate on
the following surfaces:
Note: If you must temporarily
Drive on such surfaces, cover with sheet metal or similar. One can,
however operate on poured asphalt with good surface finish.
FLOOR COVERING FOR OCCASIONAL
Occasional or infrequent
transport of heavy equipment on surfaces not suited for air bearing
transport can still be carried out if one covers the floor with, for
example, sheet metal (<16 gauge), vinyl floor sheeting or masonite board
(smooth side up). Any cracks, pot holes, drains, cable ducts, etc... must
be covered and filled with e.g. wet sand or plaster.
Air Bearings have a limited
ability to negotiate steps and sharp ramps. For example: an Air Bearing
with a diameter of 36” cannot travel either up or down from the edge of a
piece of sheet metal 0.12” Thick (the equivalent of 11 gauge sheet metal).
The sharp edge cuts through the air film and the membrane rubs against the
edge. Steps will, apart from friction, also lead to the loss of air. The
size of steps that can be handled depends in practice on the size of the
Air Bearing and the pressure used. Large, low pressure bearings with lift
can negotiate higher steps than small Air Bearings using high pressure.
The height of a step should, generally speaking, not exceed the demands on
flatness given earlier. One should always try to even out steps in order
to achieve a smooth slope or ramp.
It is obvious that the floor
must be strong and rigid enough to carry the load. Compared to wheeled
transport there is, however, a great advantage in using air bearings. Air
Bearing transport has a much better Floor loading distribution, which leads to
lower demand on the floor strength compared with wheeled transport. The
floor loading is very small in air caster transports due to the big air
cushion surface, elasticity and minor dead weight when compared with
equipment on wheels. Easily damaged floors such as parquet, linoleum,
clinker and surfaces with floor heating are not damaged during Air Film
Solving representative for more information
AMERICAN SOLVING INC
6519 EASTLAND PLAZA
• BROOK PARK, OHIO (USA) 44142