Proper Installation and Maintenance Can Prolong the Life of V-Belts
2017-1-10 View：
By John C. Robertson, maintenance reliability specialist
V-belts run longer and perform better if they are given the proper care and attention during installation, and in particular, during the following 48-hour running-in period.
This is a most critical time for V-belts, especially if they are to last for a few years. During this run-in period, the initial stretch is taken out of the belt. Also, the soft rubber surface of the belt's outer envelope is abraded away, and the belt settles deeper in the groove of the sheave.This causes the belt to run slack. At this point, the slack on the new belts must be taken up to avoid considerable slippage, frictional burning, and other irreparable damage. It is very important that the belts are checked often over the first few days of operation and are adjusted according to the correct tension until all signs of stretching have been eliminated. This practice will eliminate early damage and promote longer belt lives.
This article is intended to provide maintenance personnel with a standardized procedure for correctly installing a V-belt and the sheaves in which they operate. This, in turn, improves the mechanical efficiency of the motor and the driven mechanical equipment by reducing wear on rotating mechanical components.
This procedure provides general guidelines for the operation and maintenance of V-belt drives. It is intended to support any technical literature that may have been supplied by the belt manufacturer or their agents.
Step 1
Follow your company's safety work practices during the installation of the V-belts, including personal protective equipment policies and lockout and tag-out policies.
Step 2
Remove the safety guard from the V-belt drive area.
Step 3
Adjust the moveable plate toward the fixed component by using the adjusting screws to reduce the center-to-center distance of the driver-to driven sheaves. This reduces the tension on the belt and allows slack in the belt between the sheaves.
Step 4
Remove the old belts from the sheaves. Examine the operational surfaces to determine if any damage had forced the belts into an early demise. Look specifically for fabric wear on the sidewalls, reinforcing nylon cords, cracking caused by dry out, and oily surfaces.
Note: If any of the above symptoms are apparent, do not install any new V-belts until the root cause of the problem has been identified and corrected.
Step 5
Clean the sheaves of all foreign matter with a stiff brush that has bristles softer than the sheave surface material. Heavy-duty wire brushes can scratch the surface of the groove walls. These scratches can, in turn, tear up the V-belt's outer skin and systematically destroy the belt.
Step 6
Using the "go-no-go" slip gauges that can be obtained from a belt manufacturer, determine the condition of the V-groove in the sheave. This will accurately determine if the walls of the V-groove have been subjected to excessive forces caused by improper tension causing slippage and poor alignment between the driver and the driven shafting.
Step 7
If the sheaves do not meet these criteria or are damaged in other ways (chipped or cracked sidewalls), discard these defective parts and install new ones.
Step 8
Verify that the replacement belts are the correct size. Check with the "go-no-go" gauge to ensure the cross-section of the V-belt is compatible with the V section in the groove. The belt must ride in the groove with its top flat surface level with the outer periphery of the sheave.
Note: Never mix new and old belts regardless of the "new" look of the old one. Belts should always be installed in matched sets. This ensures that all of the replacement belts are exactly alike in all respects. Never mix belts from different manufacturers because they have different stretch characteristics, coefficients of friction, and cross-sectional areas. If the V-belts are not the same length, they will not carry the same amount of load. This will cause some of the belts to become overloaded and wear rapidly, shortening the life of the belt drive.
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