1. TYPES OF BELT CONVEYORS
A. Slider or roller bed
B. Horizontal - Reversing and non-reversing
C. Incline/Decline - reversing and non-reversing
D. Powered Feeder
E. Brake and Meter Belts
F. Metal "Piano Hinge" Belts
G. Portable
Applications
Belt conveyors are used for the controlled movement of a large
variety of both regular and irregular shaped products. They can
move light, fragile to heavy, rugged unit loads on a horizontal,
inclined or declined path within the limits of product stability
and the conveyor component capacities. The items being conveyed
are carried by the top surface of the belt.
The Hytrol General Catalog contains recommended uses for each
model of powered conveyor. This general catalog also lists
standard specifications as well as optional equipment for each
model. Study the Hytrol General Catalog carefully and often. There
is a world of good information to be gained from this practice.
Slider Bed is a belt conveyor, which utilizes a smooth
surface bed as the carrying surface for the belt. In the Hytrol
General Catalog this is a steel bed. In other applications, you
may find the carrying surface for the belt to be Masonite or other
solid bed surface.
Roller bed is a belt conveyor, which utilizes rollers as
the supporting surface of the belt. A good rule of thumb is to
have at least two rollers under the belt supporting the shortest
item being conveyed. This will give the item a reasonably smooth
ride. The selection of the size of the carrying rollers is a
function of the weight of the item being conveyed, the belt speed
and the manner in which the items are placed on the belt. Normal
loading would simply be a gravity or powered conveyor transferring
a package. This is a smooth transition such as packages
transferring from the discharge end of a gravity or powered
conveyor to the infeed end of this belt conveyor. If packages are
hand loaded onto the belt, there is a strong possibility that the
packages might be thrown and dropped onto the belt. We might
consider more rollers (twice the number normally supplied),
heavier duty rollers or slider bed in the area of impact only.
How do we select whether to offer the slider or roller bed
conveyor? If we have light loads within the load parameters
outlined in the Hytrol General Catalog, then, since cost is
usually an important factor, we would select the slider bed
conveyor. For heavier loads, again within the load parameters
outlined in the Hytrol General Catalog, we recommend the selection
of roller bed conveyor. 1.9" or 2" dia. rollers should
not be used at belt speeds in excess of 150 F.P.M. Also, very wide
conveyors require special consideration because of the possibility
of axle deflection within the rollers.
Special conditions, such as high or low temperature conditions,
and dirty or wet conditions should be brought to the attention of
your Master Hytrol Distributor prior to quoting. Relatively heavy
packages should not be transferred onto the middle of a belt
conveyor say one 20 feet or longer in length. Continual transfer
of the relatively heavy packages would have a tendency to push the
belt to the one side of the conveyor, and if these packages were
to enter the belt conveyor as a continuous flow, then could push
the belt over to the extent that the edge of the belt could
possibly be damaged at the drive or tail ends. The best type of
transfer described above would be with the use of 1ive roller
conveyors. However, if for some reason, the use of live roller
conveyors is not practical, then we should consider the use of the
three-pulley device normally furnished with the integral powered
feeder, at each side of the junction of the push-on or push-off
location. This provides a tight belt in the strategic location. A
thin strip of wood, plastic, or steel, along the one edge of the
belt opposite the push-on or push-off would also be helpful in
retaining the belt in the proper tracking position. The solutions
suggested herein are not to be construed as approval to accomplish
a specific described action, these are merely recommendations for
alleviating a non-recommended condition.
A single direction non-reversing belt conveyor of reasonable
length, may use a standard end drive with the 4" dia. drive
pulley. A reversing belt conveyor should use a center drive,
generally, with a larger than 4" dia. drive pulley,
particularly with longer conveyor lengths or heavy loads on the
belt. See the Hytrol General Catalog.
Horizontal belt conveyors usually consist of the following
listed components:
1. An end or center drive which would include a gear motor and a
take-up.
2. Either one or two end pulleys, depending upon the type of drive
used, or a power take-off device.
3. Bed sections, either slider or roller bed.
4. A suitable length of flexible belt.
5. Return idlers on approximately 10'-0" centers to support
the return strand of belt.
6. Floor or hanger supports on approximately 10'-0" centers.
7. Electrical controls and field wiring (optional).
Incline and decline conveyors: Consists of the same
components listed above except this unit would include a single or
double noseover, possible a feeder section, one of the two types
offered, and a "rough" surface belt on the incline
(decline) instead of friction surface belt.
Brake and Meter Belts
The Brake belt is used as a stop at the end of an accumulation
(Live Roller) conveyor and the Meter belt is used as the speed up
belt to obtain case separation. The Meter belt would normally have
the drive and the Brake belt would be slave driven from the Meter
belt through a power take-off similar to that used at the
chain-feeder section of an inclined belt conveyor. Meter belts
normally run 1 1/2 to 2 times faster than the Brake belt. Both
Meter and Brake belts are normally provided with a
"rough" top type belting, such as "Hilltopper".
As a rule of thumb, the total length of the combination of Brake
and Meter belts should be about 1/7 the total length of
accumulation conveyor with the Brake and Meter belts. The length
of the Meter belt, based upon the belt width would be the same as
a powered feeder section. As an example: If the total length of
accumulation conveyor with Brake and Meter belts were 84 feet,
then the total length of the combination Brake and Meter belts
would be 12 feet; then, subtracting the length of the Meter belt
would give us the length of the Brake belt portion.
Metal "Piano Hinge" conveyor: This is a hinged
steel belt, ideal for carrying hot and oily parts from punch
presses, forging machines, etc. This type of conveyor may be
level, horizontal or inclined "S" shaped as required.
The design and dimensional information is described in the Hytrol
General Catalog.
Wire mesh belt conveyor: This type of belt conveyor,
because of the open mesh, permitting the free flow of air, is
excellent for conveying hot or cold materials too hot or too cold
to handle on standard duck or PVC belts. The wire mesh belt can
travel on rollers or longitudinal runners covered with a dense
plastic material. The pulleys are generally cast with multiple
teeth to grip the mesh of the belt. Under some circumstances, the
pulleys can be standard rubber or neoprene lagged to grip the
underside of the wire mesh belt. Since it carries no load, the
return strand can also be supported by return idlers or by
longitudinal runners.
Portable conveyors: The Hytrol General Catalog lists a
large number of portable belt conveyors. A portable conveyor is
one, which can be rolled from one position to another on caster
wheels. In addition, Hytrol offers a large variety of skatewheel
conveyors or 1 3/8" diameter roller conveyors with tripod
stands and portable castered supports. The catalog also lists
various extendible portable gravity conveyors, the descriptions of
which are well covered in the Hytrol General Catalog.
Caution areas for belt conveyors: A reversible belt
conveyor has been and will, no doubt, continue to be an item with
which the operating results will be in doubt until the conveyor is
installed and tested under no load and load conditions.
Theoretically, a belt conveyor will not operate reversibly unless
all revolving surfaces in contact with the belt are square with
the frame or unless the belt tracking devices are properly
adjusted. Conveyors & Casters employs capable Millwrights who
have had extensive experience in installing and testing the
reversible belt conveyors.
When a reversible belt starts to give belt-tracking trouble, even
after it has worked for a number of years, random adjustments
should not be made. It could easily get out of hand if someone who
does not know the proper procedure tries to correct the trouble by
making various adjustments. If, after operating satisfactorily for
a number of years, it must be assumed that something must have
happened to cause the belt to run off to one side.
Before trying to make any adjustments the following points should
be checked:
1. If a new belt has been installed, has the belt been cut
perfectly square or has it been cut on a cambor?
2. Has the conveyor frame itself been pushed out of line by lift
trucks or other devices?
3. Have adjustments been made on the return idlers or the end
pulleys by mechanics inexperienced in solving such problems?
4. Have the bolts which hold the flange bearings pulley shafts
become loose and shifted from their original positions?
5. Have any of the roller conveyor bearings or flange bearings
become so worn as to effect their original square alignment?
6. Have any of the return idler supporting clips or mountings
become loose so as to affect the alignment of the belt?
It is quite possible, if all of the above items are carefully
checked and any corrections properly made that the belt will then
track in its original squared up position in both directions. The
belt tracking conditions should be approached by correcting those
things which may have gone wrong due to the age of the conveyor
components thus returning it as near as possible to its original
condition.
The practice used in tracking a one-direction belt cannot be
applied to a reversible belt conveyor. All moving parts in contact
with the belt must be squared up with one another and all with the
frame for the single direction only. Do not class a reversible
belt conveyor in the same category as a single or one direction
belt conveyor so far as installation time is concerned. The
reversible belt conveyor does take considerably longer because of
all the variable conditions herein described to install properly.
Belting: Belting manufacturers have come a long way in the
manufacture of excellent quality belting. For example, most
belting for level conveyors furnished by Hytrol will probably be
PVC (poly vinyl chloride) machine woven nearly impervious to most
liquids and ambient temperatures. The "Hilltopper" belt
has a rough surface bonded to the PVC base. Other belts, some
impervious to food oils and some approved by USDA (US Department
of Agriculture) for food handling are also available. Check with
the Hytrol Master Distributor for belt recommendations for
specific special applications.
Motors: Hytrol Conveyor Company manufacturers their own
gear reducers for most conveyor applications. The integral width
gear reducer for "V" built variable speed drives and the
"C" face reducer to receive any "C" face
electric motor. Motors are available in open drip proof and
totally enclosed, either single or 3 phase. In the Western States,
we mostly use totally enclosed motors. Hytrol reducers are
available in commercially standard speed ratios of 10 to 1, 20 to
1, etc. Hytrol Conveyor Company can provide variable speed motor
drives at additional charge. They have one which is.2.7 to 1 ratio
and another, which is 6 to 1 ratio. As an example, this means that
the 2.7 to 1 ratio can have, lets say, a low speed range down to
10 F.P.M. and can be adjusted up to a maximum of 27 F.P.M. On the
6 to 1 ratio we can have, the low speed at 10 F.P.M. and the
maximum speed at 60 F.P.M. We can adjust the low speed instead of
using 10 F.P.M. to say 15 F.P.M. with the high-speed range greater
than that stated above, within the speed capacity of the rollers,
if the conveyor is a roller bed.
Electrical Controls:
Many Hytrol portable conveyors are normally furnished with single
phase motors and with reversing drum switch all for 115 volts.
This reversing drum switch has no overload protection. When 3
Phase motors are used, then the push-button controls operating
on.115 Volt single phase which in turn actuates a 3 phase magnetic
starter which does have overload protection in the form of heater
coils. If the motor, for any reason, is overloaded and starts to
heat up in excess of its rated capacity, the heater coil
automatically will be destroyed, which, in turn, interrupts the
electrical current to the motor. The motor stops undamaged and the
condition which caused the heater coil to be destroyed, can be
corrected, a new coil replaced in the starter and the system
started up once again. It is extremely important that the proper
coil size be used. Other than portable conveyors, Hytrol does not
normally furnish electrical controls unless specifically requested
to do so, at additional charge. Limit switches, photo cells and
other controls can also be furnished at additional charge.
Conveyors & Casters is proud to report they have "in
house" capabilities to prepare sophisticated electrical
wiring schematic drawings, at additional charge and can arrange
with qualified local electrical contractors in order to provide a
turn-key installation.
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