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Narrow V-Belts

Effectively handling drives from 1 to 1,000 hp, these belts rank high in horsepower-hours per dollar, the ultimate measure of drive valve. The narrow-belt cross sections (3V, 5V, and 8V), offer higher power capacity for any sheave size and weight.

The narrow or “wedge” design provides more tensile member support than classical V-belts. Narrow belts handle an equivalent load, but with narrower face width and smaller diameters than the traditional classical V-belts. These features allow the use of smaller belts or fewer belts to transmit the load, an important a d vantage if your goal is to maximize power transmission efficiency by reducing drive weight and size.

Classic V-Belts

The most widely used V-belts are A, B, C, and D classical belts. Used more out of habit and convenience than design, these belts can handle fractional to 500-hp drives, usually at the lowest cost. However, they occupy more space, and the drives weigh more than narrow-belt drives. Also, classical belts are usually less efficient than narrow belts. But their versatility and wide range of sizes and types make them an attractive alternative to wedge belts.

Many classical belts are used for replacement because it is considered too costly to replace sheaves when upgrading from classical to narrow or other belt types. Therefore, when replacing classical sheaves, it is an opportune time to upgrade to narrow or other belt types.

Double-V or Hex Belts
A variation of the classical belt, Hex belts come in AA, BB, CC, or a deep CCP cross section. These belts transfer power from either side in serpentine drives. A drive design using Hex belts is more complicated and Goodyear’s V-belt engineering manual should be consulted when replacing or troubleshooting these drives.
FHP Belts
The 3L, 4L, and 5L light-duty FHP belts are part of the classical belt line also. As the name implies, these belts are used singly on drives of 1 hp or less.
 
Cogged V-Belts

Goodyear has a complete offering of cogged, raw-edge belts in narrow, classical, and FHP styles. Designated 3VX, 5VX, AX, BX, CX, 4L, and 5L, cogged, raw-edge V-belts have higher capacity and efficiency, and they use smaller sheaves than traditional envelope (wrapped) belts. These belts have a higher coefficient of friction and are more aggressive, which makes them a very efficient belt for power transmission.

Unlike conventional fabric-covered V-belts, raw-edge belts have no cover. Thus, the cross-sectional area normally occupied by the cover is used for more load-carrying cord. Cogs on the inner surface of the belt increase air flow to enhance cooler running. They also increase flexibility, allowing the belt to operate with smaller sheaves. With classical V-belts, certain under-designed or problem drives can be upgraded to “satisfactory” by substituting classical cogged belts for classical envelope belts without replacing sheaves.

Because of their higher coefficient of friction, cogged belts tend to be more sensitive to alignment. While envelope belts can tolerate some misalignment, cogged belts are more likely to turn over under the same conditions. Cogged belts should not be used in clutching drives, drives with severe shock loads, and drives that have changing center distances, such as shaker screens. In these applications, the aggressive nature and flexibility of cogged belts can cause vibration, belt turnover, and belt breakage. Cogged belts should also be avoided in drives that require slippage during frequent stops and starts.

Maintenance

Overview
Belt drives are a reliable and efficient means of power transmission. Since they are essentially trouble-free, they are ignored often and do not receive the minimal attention they require for the full delivery of benefits over the course of a long life of use.


Belt drive maintenance is neither complicated nor does it require a great deal of time or a large variety of special tools. Primarily, good maintenance requires that you look at and listen to the drive to discover and correct any problems.

What to Look For:

Oil and Grease
Police a drive well. Immediately repair leaky bearings as excess oil on a bearing will splash on the belts. If you cannot correct these conditions without sacrificing adequate lubrication, use oil-resistant belts as too little lubrication will cause bearing failure, which may also cause belt failure when drag becomes excessive.

Dirt
No equipment operates best when it is dirty. Belts are no exception. Dirt accelerates belt wear and dirt build-up in a V-belt sheave groove impairs traction.

Added Loads
Check to see that no additional loads have been added since the original drive was selected.

Belt Guards
Belt guards ENSURE that large debris doesn’t enter the drive.

Cracking
Do not replace a V-belt simply because you observe bottom cracking. Reduce bottom cracking by using larger sheaves and larger reverse bend idler sheaves. However, tooth cracking on synchronous belts is an early indicator of tooth shear, and therefore, the belt should be replaced. See troubleshooting charts for corrective action.

Belt Dressing
Belt dressing is seldom beneficial to belt drives. This TACKINESS actually accelerates the time to failure of V-belts. If V-belts slip or squeak, identify and correct the problem. Never use belt dressing
on synchronous belts.

Vibration
Excessive vibration should be minimized. This is often due to low tension or damaged tensile member. In extreme cases, a back side kiss idler may need to be added in the vibrating span.

  

Tension
Tension is critical in belt drives. For V-belts the ideal tension is the lowest tension at which the belt will not slip under peak load conditions. For synchronous belts, under-tensioning leads to ratcheting and excessive tooth loading. Adjust tension to the values shown in the tables provided in this Guide. See section on “Installation” for the type of belt involved for additional information.

Heat
High temperatures cause heat-aging and shorten belt life. Check frequently belts operating in temperatures above 140 degrees F and consider special heat-resistant construction if belt life is not satisfactory.

Belt Turn Over
Turned over V-belts indicate drive misalignment, worn sheaves or excessive vibration.

Change in Ride Out
Ride out is the position of the top of the V-belt to the Outside Diameter of the sheave. A change in ride out over time indicates uneven belt wear or worn sheaves.

Lateral Vibration
Don’t allow belts to snake.

Belt Wear
Wear on V-belt sidewalls indicates consistent slippage, excessive dust, or rough sheaves. Tooth wear on synchronous belts is an indication of improper tooth meshing. See trouble guide for possible causes and corrections.

Debris
Broken belts or excessive vibration can result from the presence of foreign material on the belts or in the sheaves or sprockets.
What to Listen For:
 
Squeal   Chirp
Squeal is usually a result of insuffi cient belt tension and requires prompt investigation. If squeal persists after you have checked all belts and adjusted tension, examine the drive itself for overloading.
Chirp, a sound like that of a chirping bird, can occur on all types of belt drives. Never apply dressing or oil to a belt in an effort to eliminate chirps or squeaks. Realignment of an idler may help. Chirps or squeaks are often annoying, but will not harm belts.

Troubleshooting

V-Belt Performance Analysis

 

Cause of Failure — Excessive exposure to oil or grease has caused the belt to swell, become soft and the bottom envelope seam to “open up”.
Correction — Provide splash guards, do not over lubricate, clean belts and sheaves with gasoline.

   Cause of Failure — Weathering or “crazing” caused by the elements and aggravated by small sheaves.
Correction — Provide protection for the drive and replace belt or belts.
 
Cause of Failure — Cut bottom and sidewall indicate belt was pried over sheave and damaged during installation.
Correction — Be sure to use proper length belt and move tensioning all the way “in” when installing belt.		   Cause of Failure — Severe localized wear caused by a frozen or locked driven sheave.
Correction — Determine that the drive components turn freely and tighten belt, if necessary.
 
Cause of Failure — Constant slippage caused by insufficient tension in belt.
Correction — Tension drive in accordance with the recommendations of the equipment manufacturer and this manual.		   Cause of Failure — Rough sheave sidewalls cause the cover to wear off in an uneven pattern.
Correction — File or machine out the rough spot on the sheave groove. If beyond repair, replace the sheave.
 
Cause of Failure — Belt has evenly spaced deep bottom cracks from use of a substandard backside idler.
Correction — Replace backside idler with the minimum size recommendation.		   Cause of Failure — Ply separation caused by substandard sheave diameter.
Correction — Redesign drive to use proper size sheaves.
 
Cause of Failure — Split on side at the belt pitch line indicates use of a sheave with a substandard diameter.
Correction — Redesign drive to utilize proper size sheaves.		   Cause of Failure — The load carrying member has been broken by a shock load or damage during installation.
Correction — Maintain proper tensioning and observe proper installation procedures.
 
Cause of Failure — Tensile breaks can be caused by high shock loads, foreign object between the bottom of the sheave and the bottom of the belt or damage during installation.
Correction — Maintain proper drive tension and installation procedures. Provide guard to keep foreign material from coming in contact with the drive.		   Cause of Failure — Back of the belt has been rubbing on
a belt guard or other appurtenance.
Correction — Provide adequate clearance between belt and guard or any appurtenances.
 
Cause of Failure — Excessive dust and rough sheaves combine to cause severe envelope wear and early belt failure.
Correction — Maintain sheave condition, alignment and attempt to protect drive from excessive dust exposure.		   Cause of Failure — Worn sheave grooves allow the joined belt to ride too low cutting through to the top band.
Correction — Replace sheaves and maintain proper belt tension and sheave alignment.
 
Cause of Failure — Flange wear on PD synchronous belt.
Correction — Adjust and maintain proper pulley alignment.		   Cause of Failure — Web fabric wear caused by improper
belt and pulley fit.
Correction — Check belt/pulley fit and replace worn or
out-of-spec pulleys.
 
Cause of Failure — Tooth shear caused by belt overload
condition from improper application or shock loads.
Correction — Consult engineering manual to proper application and maintain proper belt tension.		   Cause of Failure — Fabric wear caused by insufficient belt tension or pulleys which are not to the standard PD pulley dimensions and tolerances.
Correction — Maintain proper tension and replace the out-of-spec pulleys.
       

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