200-125 300-115 200-105 200-310 640-911 300-075 300-320 300-360 642-998 QV_DEVELOPER_01 400-101 700-501 117-201 70-696 700-505 600-199 400-351 300-207 TE0-141 100-105 300-101 300-206 300-070 70-417 210-260 210-060 200-355 300-208 CISSP 300-135 210-065 300-209 70-243 70-480 CCA-500 2V0-621D 210-451 400-051 E05-001 1Z0-052 70-410 640-916 VMCE_V9 810-403 070-464 070-243 700-802 70-246 FCBA GPHR DEV-401 C2090-610 SY0-401 712-50 ADM-201 700-039 312-50 MA0-101 648-244 SK0-004 ASF 70-494 70-673 500-005 1Z0-060 C9560-503 640-875 N10-006 98-367 70-534 NS0-505 70-342 CHFP 070-410 640-878 1V0-603 1Z0-804 C8010-250 312-50V9 C2150-508 98-368 CLOUDF 70-411 70-461 220-901 70-488 070-341 PK0-003 E20-547 70-412 70-686 500-285 CISM 101-400 102-400 PDM_2002001060 JN0-100 642-883 CAP 070-347

Technical

Belt Construction
Flat woven endless belts are used on a wide variety of equipment for many different applications and specific end uses. Their uses vary from extremely sensitive drive applications, such as instrumentation, recording devices and sensitive weigh-pan conveying applications, to light and medium duty uses, such as currency and check transports, film transports, paper handling and vacuum transporting sections of business and office machinery, all the way up to high speed grinding, spindle drives, wire drawing applications, woodworking equipment and textile machinery drives. The variety of possible applications require an extremely wide range of specific physical properties that will enable each belt to perform its task continuously, with good reliability throughout its life.

Flat woven endless belts combine many desired features, such as a good strength/ thickness ratio, adaptability to a wide range of speeds (from slow moving conveying to the driving of grinding spindles up to 100,000 RPM), quiet vibration-free operation; truly endless construction (no joints or seams to inhibit flex life), excellent dimensional stability and uniformity throughout their length, and maximize efficiency because the pitch line of the belt is close to the surface being driven.

Belt Types
When the various yarn types are woven using different combinations of yarns and weave patterns and then combined with specific elastomers, the general types of belts are produced. These types are referred to as STABLE, SEMI-STABLE,SEMI-STRETCH and STRETCH.

Stable belts are used on drives having some means of belt tensioning, such as a movable pulley location or an external tensioning pulley, either spring loaded or locked in place after tensioning of the belt is completed.

These belts are typically used on individual belt drives or group drives where each belt is separately tensioned. Applications include high-speed power transmission, woodworking machinery, card readers, sorters, and printing machinery.

Semi-Stable belts allow the use of multiple belts with common take-up, or length adjustment. They can be used on wide belt conveying and on applications requiring good edge wear resistance for flanged or guided tracking. Specific applications include paper handling, food conveying (FDA approved) and check-weighing.

Semi-Stretch/Elastic belts were designed for fractional horsepower drives requiring a controlled stretch belt to provide the driving tension, at a specified circumference, when length adjustment or external tensioning is not available. Their major uses are as low-tension drive belts using fixed-center pulleys and as paper transport belts used in multiple sets on a common shaft, with either common take-up or no take- up at all (fixed-centered shafts). These belts are found in business and office machines, currency transports, vacuum transports,instrumentation, disk drives and film transports.

Stretch/Elastic (no woven carcass used) belts find similar applications to those of the semi-stretch types but provide greater range of elasticity, at a lower tension, per equivalent belt widths. Common applications include light-duty drives, paper, film and currency transports, vacuum transports and light-duty conveying.

Drive Considerations
There are a number of factors to be considered before selecting a particular belt style for a specific application. Two of the most important factors to be addressed are the type of drive configuration and the provisions for belt tensioning (or lack thereof). The first thing to look at is the number of belts required to satisfy the application requirements and the overall geometry of the belt path, including sizes and number of pulleys.

Type of drives:

  • Individual, single drive, two pulleys
  • Open, crossed drive and quarter turn (90 degree twist)
  • Multiple-Belt Groups or Sets
  • Multiple pulleys (serpentine), four pulley quarter turn (mule drive), multiple belts on common shafts with backside idlers, multiple belts common tensioning or fixed-center shafts.

The next considerations are the allowable space to accommodate belt width and the type of pulley on which the belt will run. Is the pulley face open or are flanges used to retain the guide belts? Are any pulleys crowned for guidance and belt tracking? If so, what type of crowning is being used and how severe is the crown? What is the face width of the open pulleys or what is the dimension between the flanges? These answers are required for proper belt selection.

Not all belts are designed to withstand running against flanges. Most types of flat woven endless belts will track well over a minimum of pulley crowning. If flanges are required, always use straight sides at 90 degrees to pulley face surface and maintain sharp corners, minimizing any rounding which causes the belt to climb the flange.

General Crowning

Circular/radius crowns are preferred over bevels with flats.

For belts up to 3″ wide:
Min. Crowning=1.6% of belt width (1″ belt=.016 crown)
Max. Crowning=2.5% of belt width (1″ belt=.025 crown)

For belts over 3″ wide:
Min. Crowning=0.5% of belt width (5″ belt=.026 crown)
Max. Crowning=1.6% of belt width (5″ belt=.080 crown)

crowning

Unless unusual tracking problems exist, minimum recommended crowning should be chosen, since ideal properties are developed through uniform belt to pulley contact. If an extreme crown is chosen for use with a stable belt, the full belt width will not be able to stretch and conform to the pulley crown, leaving the percentage of the belt width, not the pulley width. Crown choice is primarily affected by belt styles, installation tension and the degree of precision found in the machine drive alignment.

Additional considerations include specific drive details such as required torque or horsepower to be delivered, pulley diameters and drive speeds which must be known for proper belt selection and adequate belt sizing for the application.

Any adverse conditions which the belt may encounter, such as extreme temperatures, hostile chemical environments or severe abrasion should be considered as should other specific properties required, such as specific belt thickness, anti-static requirements or FDA approval.

Belt Calculations
The length or circumference of a flat belt is measured along its inside surface, or along that surface contacting the pulleys. When drive details are not available, a close determination of the belt path length can be made by using a wire or a steel tape, pulled taut around the pulleys. This measured distance is referred to as the drive circumference. The actual manufactured belt length may vary from the measured distance depending upon the amount of built-in tension or elasticity required for the specific style of belt, and the type of tension or take-up available on the machine.

L = Belt Length
C = Centerline Distance (distance between centers of the two pulleys)
D = Outside Diameter of Larger Pulley
d = Outside Diameter of Smaller Pulley
π = 3.14159

L = π D + 2C
Two pulleys, equal diameters, open-drive configuration
L = 2C + π (D + d) + (D – d)2
2 4C
Two pulleys, unequal diameters, open-drive configuration
L = 2C + π (D + d) + (D + d)2
2 4C
Two pulleys, unequal diameters, cross-drive configuration

Belt Tension

belt_motionFlat endless belts have a maximum operating or working tension equivalent 10% of their breaking or tensile strength. Total tension (see discussion below) on a belt should never exceed the operating or working tension.

Belts in motion on pulleys develop tight side tension (T1) slack side tension (T2). Tight side tension is created on that section of belt approaching the driveR pulley. Slack side tension is created on the section of belt approaching the driveN pulley.

These tensions are illustrated as follows:

Tight side tension plus slack side tension is equal to to total tension (TT).
This can be stated as T1 + T2 = TT.

Tension available to do work is stated as effective tension (Te). Effective tension can be found by subtracting slack side tension from tight side tension (Te = T1 – T2) or can be computed using the following formula:

Te (in pounds) = 33,000 X Horsepower (hp)
Belt speed in feet per minute

Please contact the factory for complex drives and any questions.