Industrial Belt Conveyors Idler Belt Conveyors

Union Iron Idler Belt Conveyors are used extensively in long span, high capacity materials handling operations. The Union Iron series 2000 designs are extremely rugged performers affording years of efficient service. The idlers are constructed to meet CEMA standards with factory lubricated bearings for extended life. All idler assemblies are corrosion resistant and install easily on new or existing frames. Union Iron Works also supplies belting and drive equipment for Idler Belt Conveyors.

Belt Troughing Idler Systems have been in the past the most popular bulk material conveyors. Idler conveyors are the most economic because of higher capacities and greater distances than any other mechanical conveyors. Belt conveyors are capable of handling a wide variety of materials from very fine to granular or lumpy, from very free flowing to sluggish, from non-abrasive to very abrasive. The only type of material to watch out for in belt conveyors are materials of irregular shape or having sharp edges. The single most expensive item on a belt conveyor is the belt itself. The belt can represent about a third of the total cost. The repair and replacement is the biggest maintenance expense. One way to insure maximum belt life is to select the right conveyor idler, and the proper idler spacing. HP calculations are based on frictional and gravitational forces acting on the belt.

Transition Areas

The distance required to form a flat belt into the shape of a trough or back to a flat belt usually located at head and tail pulleys. Transition idlers are not used with 20 degree idlers. Transition idlers are used on 35 degree and 45 degree troughing idlers. The quick transition from a flat to a trough shape places stress on belt edges and draws the belt into the idler gap which will cause the greatest amount of damage to a belt. Transition idlers eliminate this problem by troughing the belt gradually.

Impact Areas

The area where material comes in contact with the belt, which can cause high impact loads on the belt. Material with coarse lumps may even cut the conveyor belt, so impact idlers are used in this area. The idlers are spaced close together to absorb impact loads.

Normal Troughing Idlers

Idler spacing other than transition and impact area, spacing is based on the weight of material, size of idlers and allowable belt sag. Care should be taken in picking out proper idlers. Such items as operating time and atmosphere conditions, should be considered in selecting idlers.

Return Idlers

Return Idlers are mounted on the underside of the conveyor. The idlers have only the weight of the belt to carry. When the return idler has belt tension acting on the rollers, a bend pulley with a larger shaft is recommended.

Training Idlers

Return idlers and troughing idlers trainers are used to prevent belts from misalignment. Training idlers should be placed a minimum distance from terminal pulleys and at appropriate distances for the balance of the conveyor.

Screw Take-Ups

Use on light duty, short centers or frequently adjusted conveyor. They should be used only when, due to space limitations or other conditions, it would be impossible to use the gravity type. Screw take-ups put a greater amount of tension on belts causing wear on shafts and bearings.

Gravity Take-Ups

Are far better for belt conveyors than screw take-ups. Some advantages are maintaining constant belt tension, adding no more belt tension than to prevent excessive sag, minimizing power requirements and wear on shafts, bearings and driving equipment, and reducing the number of times a belt must be shortened and spliced.

Belt Loaders

The method of loading the belt is important. Proper loading helps prolong belt life, reduce spillage and keep the belt trained. The design of belt loaders is varied by such conditions as capacity, material characteristics, belt speed and belt inclination. The object of a belt loader is to:

A. Load material on the belt at a uniform rate.
B. Load material on the belt centrally.
C. Reduce the impact of material on the belt.
D. Deliver material at a velocity close to belt speed.

Head And Tail Pulleys

Pulleys should be of the crown face type for belt training. Heavy duty shafts to take normal running belt tension plus any surges in power requirements. Head pulleys should be lagged to prevent belt slippage.

Miscellaneous Items To Consider

Miscellaneous items to consider for a complete system are: Discharge hoods, conveyor hoods, belt wipers/cleaners, side skirts, belt alignment devices, motion speed switches, snubber pulleys, take-up frames, trussed bridge work, support frames and loading/unloading chutes.

Dimension Chart

20 Degree CEMA II Troughed Belt Idlers (Equal length rolls and return belt idlers)
Belt Width	B		C	D		F		G		R	M
	4"	5"		4"	5"	4"	5"	4"	5"
14	16 1/4	15 7/8	23	7 3/16	7 11/16	9 1/16	9 7/16	5 1/4	5 1/8	5/8	16 5/8
16	18 1/8	17 3/4	25	7 3/16	7 11/16	9 5/16	9 11/16	5 7/8	5 3/4	3/4	18 5/8
18	20 1/4	19 7/8	27	7 3/16	7 11/16	9 9/16	9 15/16	6 5/8	6 1/2	7/8	20 5/8
20	22 1/16	21 9/16	29	7 3/16	7 11/16	9 3/4	10 1/8	7 1/4	7 1/8	1	22 5/8
24	26	25 5/8	33	7 3/16	7 11/16	10 1/4	10 5/8	8 5/8	8 1/2	1 1/4	26 5/8
30	31 3/4	31 3/8	39	7 3/16	7 11/16	10 15/16	11 5/16	10 5/8	10 1/2	1 1/2	32 5/8
36	37 1/2	37 1/8	45	7 3/16	7 11/16	11 5/8	12	12 5/8	12 1/2	1 7/8	38 5/8

35 Degree CEMA II Troughed Belt Idlers (Equal length rolls and return belt idlers)
Belt Width	B		C	D		F		G		R	M
	4"	5"		4"	5"	4"	5"	4"	5"
14	15	14 1/4	23	7 3/16	7 11/16	10 3/8	10 11/16	5 1/4	5 1/8	1 1/4	16 5/8
16	16 5/8	15 15/16	25	7 3/16	7 11/16	10 11/16	11 1/16	5 7/8	5 3/4	1 3/8	18 5/8
18	18 5/8	17 15/16	27	7 3/16	7 11/16	11 1/8	11 1/2	6 5/8	6 1/2	1 1/2	20 5/8
20	20 1/4	19 9/16	29	7 3/16	7 11/16	11 1/2	11 13/16	7 1/4	7 1/8	1 3/4	22 5/8
24	23 7/8	23 3/16	33	7 3/16	7 11/16	12 5/16	12 5/8	8 5/8	8 1/2	2 1/8	26 5/8
30	29 1/8	28 1/2	39	7 3/16	7 11/16	13 7/16	13 13/16	10 5/8	10 1/2	2 3/4	32 5/8
36	34 7/16	23 3/4	45	7 3/16	7 11/16	14 9/16	14 7/8	12 5/8	12 1/2	3 1/4	38 5/8

45 Degree CEMA II Troughed Belt Idlers (Equal length rolls and return belt idlers)
Belt Width	B		C	D		F		G		R	M
	4"	5"		4"	5"	4"	5"	4"	5"
14	13 5/8	12 9/16	23	7 3/16	7 11/16	11 1/16	11 3/8	5 1/4	5 1/8	1 1/2	16 5/8
16	14 7/8	14 1/16	25	7 3/16	7 11/16	11 7/16	11 13/16	5 7/8	5 3/4	1 3/4	18 5/8
18	16 11/16	15 7/8	27	7 3/16	7 11/16	12	12 5/16	6 5/8	6 1/2	2	20 5/8
20	18 3/16	17 3/8	29	7 3/16	7 11/16	12 7/16	12 3/4	7 1/4	7 1/8	2 1/16	22 5/8
24	21 1/2	20 11/16	33	7 3/16	7 11/16	13 7/16	13 3/4	8 5/8	8 1/2	3 1/4	26 5/8
30	26 3/8	25 9/16	39	7 3/16	7 11/16	14 13/16	15 1/8	10 5/8	11 1/2	4	32 5/8
36	31 3/16	30 3/8	45	7 3/16	7 11/16	16 1/4	16 9/16	12 5/8	12 1/2	4 3/4	38 5/8

** Variable depending on application
CEMA - Conveyor Equipment Manufacturers Association
Idler Belt Conveyors Also Available In CEMA III And IV Designs