1. Belt Conveyors
By. Benjamin Gagne

2. Background
There are many different kinds of conveyor systems out there. First what is the basic idea of a conveyor system, how and why is it used in many of today’s industrial settings. A conveyor system is used to get a item for one place to another, this item can be large, small, irregular shape, light or heavy. Not only can conveyors move items from one point to another it can be used in an assembly line so as the product is going through the conveyor it is being made or assembled. Conveyors can move items up an incline or vertically with another conveyor sandwiches the item in place. These are versatile tools for production in the industry world if the right one is implemented for a job.

3. Standards
Some companies in the industry will require a belt conveyor system to meet a certain standard. These standards insure the safety of the conveyor but also effectiveness of it.
Different standards: DIN (German), ISO (World) , BS (UK) , CEMA / RMA (USA), AS (AUSTRALIA), JIS (Japan), GOST (Russia)
Standards will include handling and storage of belts, strengths of belts, and dimension restrictions of each part in the system.
Shut off switches for operators and adequate safety shields and guards required to meet OSHA standards

4. Basic Design Available in: 45⁰ 90⁰ 180⁰

5. Motors
Sizing a motor can be very difficult and sometimes takes trial and error.
Items to consider when sizing the motor.
Belt/slider coefficient of friction
Pillow block and idler roller bearing friction
Skirt board friction
Friction due to belt flexure
Amount of load the conveyor is going to see
Belt speed
Basic idea is to know all the forces working against the motor.
1 HP equals 33,000 ft-lbs per minute. Belt speed will be in ft/min and belt pull in lbs.
Belt speed x Belt pull = Required HP

6. Transmissions
A transmission is used to get the power from the motor to the belt. It can be a direct drive but a transmission is typically used when the system needs to be geared down.
Transmissions are also to provide more power to the conveyor system if speed wasn’t crucial. This is called “gearing down” .
This can work the other way by “gearing up”, if the power isn't such and issue and speed is needed. Typically speed isn’t a problem encountered with motors.
Standards require efficiencies not drop below a certain level. Depending on transmission style efficiencies can range on 70%-95%

7. Belts
The actual belt of a system is determined on what the conveyor is going to be used for. Items to consider when choosing a belt.
Size of items being moved
Weight of items
shape of items
This will help decide what belt to use so coefficients of friction can stay low so the motors wont be over worked.
Belts are typically made from cotton, canvas, EPDM, Kevlar, nitrile, nylon, polyester, polyurethane/urethane, PVC, rubber, silicone, steel cord, Teflon, wire mesh or weave.

8. Some Useful Calculations
TC = F1 x L x CW
F1 = .035" [Normal friction factor for average conditions (over 20°F) to move empty belt.] L = Belt length (ft.) CW = Weight of conveyor belt components. 
TL = F2 x L x MW
F2 = .04" [Normal friction factor to move load horizontally.] L = Belt length (ft.) MW = Material weight (lbs. per lineal foot). MW =      33.3 TPH/Belt Speed (fpm) or Total material load in lbs/L.
TH = H x MW
H = Difference in elevation of terminal pulleys (ft.)
TE = TC + TL + TH
TE = Effective belt tension
CW Factors
Belt Width
CW Factor for 5” pulleys
12” 12
18” 18
24” 24
30” 30
36” 36
Note: for 4” pulleys multiple by .85

9. Useful Sites
Here are some useful links when trying to find certain information and or need to calculate something on a conveyor belt system.
Sizing a belt: Belt Sizing Calculator
Belt Tension and motor sizing : Motor & Belt Tension

10. Any Questions?