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Flexible Section Systems, like the VULCAN-VULCAP Vulcaflex®  OTR Repair System will do a similar job.  Flexible Systems are more labour intensive due to set-up and cannot provide the same pressure as rigid Section Molds do.  The advantage however of a Vulcaflex® system is that the full OTR tire range can be repaired with one system with the proper accessories.   

The results achieved in a VULCAN-VULCAP Section Mold is a good compression mold with adhesion values exceeding 100 between patch and tire due to pressure applied during curing. The use of uncured cushion with a semi-cured patch eliminates the problem of air pockets. The shape of the patch may not conform to the inside contour of the tire and therefore careful stitching should prevent most air pockets. It is important that the repair is done in the relaxed state of the tire. In other words, at the 3 or 9 o’clock position of the tire when it is resting on the floor. The use of patches as described above with proper heat, pressure and temperature applied in a VULCAN-VULCAP Vulcanizer assures optimum compression cure. This means no under-cure or over-cure of material.

During proper curing (pressures guaranteed by a VULCAN-VULCAP Vulcanizer), materials will flow, air pockets are eliminated and when the tire flexes and heats up during operation, there will be no tendency for the patch to leak or cause under-inflation. In a VULCAN-VULCAP Vulcanizer, the patch and plug are cured in a single operation. Relatively large areas of the tire depending on maximum patch size can be properly cured in a single operation.

Earlier models of Vulcanizers had solid cores or mandrels, which were heated. However, this method was replaced with the flexible models where air mandrels, internal and external airbags together with heatpads are used for a broad range of tire sizes. The old solid cores were only practical for a specific shape of tire, usually bias type, whereas the new method allows the system to conform to each tire (whether radial or bias tires) under repair.

VULCAN-VULCAP Vulcanizers will provide heat and pressure without distorting the tire. The MV series, although big for large tires, is still truly portable and reasonably priced. Time, temperature and pressure are the 3 critical elements to successfully vulcanize a repaired tire injury. VULCAN-VULCAP Vulcanizers supply all 3 elements with their unique Section Repair Mold Systems. To repair today’s radial tires distortion free, VULCAN-VULCAP Section Repair Molds with inflated mandrel systems will supply:

1. Correct pressure both inside and outside the tire.
2. Provide even pressure over the injured area.
3. Heating units for both inside and outside with molded heatpads to allow controlled curing temperatures for good solid cure.
4. Time, which is very critical as rubber cures at different rates.

VULCAN-VULCAP INDUSTRIES INC. - The World Leader in Section Repair Equipment supplies these important elements with their Section Repair Molds, MV Series, Vulcaflex® and VRC OTR and VTRC Truck, Tractor and Grader Tire Repair Clamps.


To successfully vulcanize a repaired injury in a tire, three things are needed:

Time, Temperature and Pressure

VULCAN-VULCAP  Industries supplies all three with our unique Section Repair Mold Systems.  Molds are compact, rugged and light-weight.  The unique Airbag System provides even pressure.  The thermostatically controlled heating pads supply the correct curing temperatures.  The experienced operator then has to ensure proper curing times.

From  the smallest passenger tire through to the largest  OTR  (earthmover) tire, we have a proven system for your tire repair operation.

We repair today's radial tires distortion free by using our VULCAN-VULCAP Inflatable Mandrel System.  A shaped air mandrel is utilized that grows to fit the tire you are repairing, using an air differential control panel, supplying the correct pressure both inside and outside of the tire, providing even pressure over the injured area.

Heating units for both inside and outside are provided with moulded Heatpads, which are controlled at curing temperature for a good, solid cure.  Time is very critical, as rubber  cures at different rates.  Follow carefully  the instructions of the rubber manufacturer.

As all VULCAN-VULCAP Section Molds cure from both inside and outside generally, a curing cycle of approx. 4 minutes per ¹/₃₂" of rubber thickness (depending on type of rubber) can be cured, temperature being held at approx. 280-300°F automatically.  Please determine exact curing times for the rubber you are using from the manufacturer!

VULCAN-VULCAP offers a complete line of Section Molds and it is easy to pick the right model  for your tires, as each Mold is designed to handle a particular tire size and range:

1.     VULCAN-VULCAP MPB  Section Repair Mold for passenger, industrial and commercial truck tires from 
       10" in rim size through 16"  =  10", 12",  13",  14", 15" and 16".   
   

2.     VULCAN-VULCAP  RTV-12  Radial Tire Vulcanizer covers truck tires from 8.25 x 15 through 1200 x 24 and our V-14 covers truck 
   tires 8.25 x 15 through 1200 x 24.
   

3.     VULCAN-VULCAP  V-14 Section Repair Mold with built-in air operated tire spreader for radial and bias truck 
   tires 8.25 x 20 - 12.00 x 24.
   

4.     VULCAN-VULCAP  MV-20 Section Repair Mold covers truck, tractor, skidder and grader tire sizes.  Truck 1400 x 24 to 1800 x 22.5, 
   tractor 12.6 through 18.4 x 38 and Skidder/Grader tires 1200 x 24 through 17.5 x 25.
   

5.      VULCAN-VULCAP  MV-30 Section Repair Mold covers tractor, skidder, grader, earthmover and OTR sizes from 1800/24/25 through 
   26.5, 1800 x 20.5, 23.5 x 2100, 2400 x 26.5-25.  With the addition of an optional top clamp extension this model will handle 
   tires up to 29.5 x 25/29.
   

6.     VULCAN-VULCAP MV-40A Section Repair Mold covers OTR tires from 29.5 x 29 to 37.5 x 51, 29.5, 33.5, 33.25, 27, 33, 49, 30.00 x 51, 33.00 x 51, 37.5 x  51.
    

7.      VULCAN-VULCAP MV-50A Section Repair Mold covers OTR tires from 36.00 x 51 to 40.00 x 57 including the new generation 
   sizes 50/80/57,54, 5/80/57 and  53, 5/85/55.
   

8.      VULCAN-VULCAP Vulcaflex®  OTR Curing System covers all tire sizes from 13.00 through 55.5/85-57 with one system 
   with the purchase of all required Heatpads and Airbags.
   

9.      VULCAN-VULCAP VRC OTR Tire Clamp  for smaller repairs on tires from 20.5 x 25 to 45/65/45.

The rigid VULCAN-VULCAP Section Repair Molds are designed for a specific tire range per model for quick set-up and high pressure curing.  The Vulcaflex® OTR System takes longer to set-up, however, with the proper accessories will accommodate practically all sizes of OTR tires.  The VULCAN-VULCAP VRC OTR and VTRC Truck, Tractor and Grader Tire Repair Clamps will do smaller repairs efficiently and distortion free.

Please Note:  The art of repairing tires lies in the hands of your tire repair man.  He must  inspect,  skive, cement and  build the repair.  VULCAN-VULCAP Section Repair Vulcanizers will cure the repair the way the repair was built.

A repaired tire rarely fails if the right time, temperature and pressure is utilized during the Repair/Vulcanizing process.  VULCAN-VULCAP Section Repair Molds and Systems are designed and built to guarantee these three critically important elements in the repair process.  It is the partnership between the skill and art of properly patching the area of the tire injury and vulcanizing it subsequently that will guarantee a perfect  repair consistently.

All VULCAN-VULCAP Heatpads are built to  and  standards and certified to .

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TECHNICAL FACTS - OFF THE ROAD TIRE REPAIR
Options for Repair
“C” Clamps vs. Vulcanizers

There are various methods of Section Repair used in the marketplace. These machines are commonly referred to as "C" Clamps. These units often use chemical patches after the plug has been cured, giving rise to possibly the following problems especially on off-the-road tires:

Assuming that the “C” clamp operator is using a chemical patch, after the plug has been cured, there are the following problems with off the road repair using this method:

a)  The chemical patch is precured in a given shape which may or may not fit to the inside radii of the tire.  Accordingly, the patch may not fit perfectly to the contour of the tire and air pockets can be created between the patch and the inner liner.

b)  The chemical materials result in a tack or bond wherever the patch touches the inner liner first, again creating air pockets and the impossibility of clearing them out from between the patch and the inner liner.

c)  The patch then cures by the chemical acceleration, the way it has been applied to the inside of the tire, i.e., there is no flow of the rubber into the air cavities.

d)  Assuming it is a tubeless off the road tire, there is no pressure being applied to the patch during the curing process, with the result that as the patch was inserted this is how it will remain.

e)  Failure of the patch then is likely to occur as the tire is flexing in operation, the air pockets expand until finally there is migration and a leak between the patch and the inside of the tire, which can potentially result in under-inflation of the tire and overloading with eventual failure of the repair.

f)   The plug area, cured with a “C” clamp and presuming that pressure and heat are applied from both inside and outside of the tire, will normally cure properly. However, any available size “C” clamp may not cover the full area of the injury that requires repair and likewise it may not conform to the contours of the tire inside and out, causing further problems.

g)  Most “C” clamps usually are unable to supply the high force required for a good compression cure.

Autoclave Repair of Earth Mover Tires

a)  The problem, of course, with an autoclave is the high cost of the autoclave and particularly for the large diameter tires required, such as 40.00 x 57 and larger.

b)  Assuming that an uncured patch is used on a tire to be cured in the autoclave and the patch is stitched very carefully onto the inside of the tire, the possibility of air pockets between the patch and the inner liner is substantially less.  On the other hand, due to the fact that there is no flow in this process, i.e., again how the patch is stitched in is the way it will remain.  The chances for this type of repair to stand up are better than the chemical patch but still relies on the quality of the operator and his ability to eliminate air pockets between the patch and the casing.

VULCAN-VULCAP Vulcanizer Repair

The key to the VULCAN-VULCAP repair is that the rubber flows in the course of curing both in the plug area and between the patch and the inner liner of the casing.

1)  The flow will result in air pockets being filled and a dense, sealed repair achieved that will not leak and fail prematurely.

2)  During the curing process, 45 lbs. of pressure is applied to the patch and next best situation would be with a plug area, both inside and outside, which results in adhesion values exceeding 100 between the patch and the tire due to the pressure applied during curing.

3)  The use of a semi-cured patch, with lots of cushion between the patch surface and the inner liner, with extra cushion applied around the edges of the patch for sealing purposes is optional.  The uncured cushion with semi-cured patch will eliminate air pockets, however, the shape of the patch may or may not conform to the inside contours of the tire and care must therefore be exercised to prevent air pockets as much as possible in the stitching process.

4)  Using a semi-cured or uncured patch with proper heat and pressure applied assures an optimum cure, i.e. there is no under-cure or over-cure of the materials.

5)  With proper curing, the materials will flow, air pockets will be eliminated, and there will be good pressure and adhesion to the extent that as the tire flexes and heats up, there will not be a tendency for the patch to fail, leak or cause under-inflation.

6)  The benefit of a VULCAN-VULCAP Vulcanizer likewise is that the patch and plug are cured in a single operation and that a larger injury area can be properly cured in a single process at one time.

7)  VULCAN-VULCAP provides flexible internal and external air bags and heat pads for a broad range of casing sizes to conform to the tire and provide the proper heat and pressure without distortion.

8)  The VULCAN-VULCAP MV series of portable Vulcanizers for off the road tires are light, portable and very reasonably priced to handle the whole off the road range of tires from 1800 through 40.00 x 57 in four separate machines:

•     MV-20 - 14.00 to 1800

•     MV-30 - 20.5 to 29.5 with extension clamp

•     MV-40 - 29.5 to 37.5

•     MV-40A (Adjustable) – 27.00 x 49 to 37.5 x 33

•     MV-50 - 36.00 to 45/65/45 including new generation sizes

•     Our portable VULCAN-VULCAP Vulcaflex® OTR System with either digital Control Panel or advanced Vulcatouch® Control Panel will accommodate the smallest to the largest OTR tire with the appropriate Heatpads and Airbags.

Earthmover Techniques and Preparation

There are some keys to ensuring that preparations of repairs in tubeless, off the road repairs are successful:

1)         Skiving of the Plug and Injury Area:

The objective is to remove a minimum area from the casing and, accordingly, rather than the "hourglass" type of skive, the injury should be prepared with a straight through the casing area with a slight bevel, both on the inside of the casing and the outside.

There is equipment available that can improve the preparation of the plug area to ensure that there is good bonding and no glazing or burning of the material.  A radial injury including side wall should likewise be prepared with a minimum elimination of the cord body of the tire.

2)         Liner:

If the inner liner is solidly bonded to the casing, it is not necessary to remove the inner liner in the patch area, but it does have to be prepared for best adhesion.  It is important, that any silicone or other mold release agents that are on the surface of the inner liner, be washed off from the patch area with material such as Siliclean.  This ensures that the silicone or foreign materials are removed from the area prior to buffing and preparation, so that the silicone is not worked into the inner liner, causing potential failure of the patch bonding layer.

3)         The inside should be buffed slightly beyond the patch area, but should not be burned or glazed to attain a good bonding and adhesion base.

4)         A small amount of cushion gum should be applied throughout the plug area for best flow and bonding, after which conventional rubber can be used either with an extruder gun, or strips can be stitched into the plug area.  The patch should be applied very carefully on the inside, stitching from the plug area outwards to eliminate all possible air pockets.

5)         VULCAN-VULCAP recommends a layer of cushion gum on top of the edges of the patch to provide better sealing and flex characteristics.

6)         With VULCAN-VULCAP'S MV series Section Molds the patch and plug will result in an almost invisible repair with maximum adhesion values.  If proper repair procedures are followed, repaired injuries can be guaranteed for the life of the tire, as a true vulcanizing repair is accomplished.

7)         Should an inner liner be separated in the injury area, it should be removed and with careful buffing to the first layer of the casing, the inner liner materials should be replaced with cushion gum prior to applying the patch.  In the case of radial tires, the steel cord must be carefully prepared to eliminate all rust.  It needs to be buffed until it is bright and shiny and then coated with cement.

Conclusion:

It is the partnership between the skill and art of properly preparing and patching the area of the tire injury and vulcanizing it subsequently with the proper equipment that will guarantee a perfect repair consistently.

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HELPFUL INDUSTRY INFORMATION

Reprinted with permission from Retreading Business Issue 2008/3

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The above printed with permission from Today's Tire Industry Magazine 

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