What you need to know for your industrial track and wheel system
Industrial steel wheels are used in places like manufacturing, mining, and storage to run carts and other equipment along tracks. Production on rails is orderly and predictable. Track systems also save energy and maintenance compared to wheeled vehicles. Before you order wheels, take time to consider the specific needs of your application.
What are these wheels going to be used for?
Although metal wheels all may look similar, low RPM wheels used in industrial applications are not the same as the high-capacity, high-velocity wheels used by trains, subways, and light rail.
Materials, manufacturing processes, size, working profile, safe working load, and the bushings or bearings used in high velocity applications are all quite different to those needed for low RPM applications. A fast-moving train needs to deal with braking, corners, load redistribution, and efficient transfer of power to the wheels.
Reliance Foundry’s industrial wheels are rated for 3 mph and lower.
What metal should industrial wheels be made from?
Different alloys are used for high speed vs. low speed industrial wheels.
Anything moving people also tends to use high speed train wheel standards even if they move more slowly, for safety factors. ASTM A551 specifies the carbon steel alloys used for these purposes. The steel alloys must be heat treated to withstand the high velocity, high RPMs, heavy loads, and severe braking. In some places it may be AISI 1060 or 1070 carbon steels specified.
Low speed does not need the same composition or heat treatment to deliver solid performance. Cast carbon steel industrial wheels that work at low speed need to be tough, designed to handle the working load they’re given, but do not need the same tolerance for braking or friction. We generally use ASTM A915, Grade SC1040 for our cast steel, and ASTM A29 Grade 1045 steel for forged or machined parts.
Read more on wheel materials: Steel vs. Iron Industrial Wheels
Do I need single or double flanged wheels?
Single flanged wheels have a rim that hugs the track from only one side of the wheel. A double flanged wheel has rims on both sides.
Single flanged wheels are kept on precisely-spaced tracks by way of their axle, which places the flanges at the proper distance apart. Single flanges are more often used for trains and high-speed rails because it is single flanges that allow for traditional switches and frogs—devices that allow a train from one track to another—whereas double flanged wheels are best for moving along a single track. Double flanged wheels provide a bit more security, however. If there is debris on the track, or slight shifts in the rail, a double flanged wheel will help prevent derailing.
Read more on flanges: Single and Double Flanged Wheels
What is the safe working load?
Industrial wheels come with a safe working load, calculated based on their material, size, and structure. This load is calculated for dynamic, moving applications.
To figure out the safe load per wheel, the cart and weight of the freight in the cart must be added, and then multiplied by a safety factor, often of 25%. For example:
Total Working Load = (Cart Weight + Load Weight) x 1.25
Check with the engineer for your application to ensure this is the appropriate safety factor.
Each wheel must have a safe working load greater than or equal to the working load divided between number of wheels on the cart.
Safe Working Load per Wheel = Total Working Load / Number of Wheels
Read more about SWL: How to Assess Safe Working Loads for Wheels
What size industrial wheel should I get?
With any application, there is a balance between function and cost. Larger wheels mean lower rotations per minute, which means more distance travelled per rotation: as a simple machine, a larger steel cart wheel offers mechanical advantage. However, a bigger wheel requires greater torque, and so needs increased power from the engine.
Most industrial carts, then, use the smallest wheel they can. Bigger wheels may be important if the cart’s chassis needs to be raised high enough to pass over debris or items on the track.
Read more about the physics of wheels: The Wheel: A Complex Simple Machine
What shape tread should my metal wheel have?
Steel cart wheels can have different profiles across the tread.
The working surface of the wheel is involved in keeping it on the track, cornering efficiently, and lowering friction. On rails with curves, a taper across the surface gives the train the ability to curve through turns. A rigid axle keeps the two wheels the same distance apart and rotating at the same RPM, but the taper means that one of the wheels is covering more distance than the other, allowing the train to move along a bended path.
Most double-flanged industrial wheels do not to deal with big curves in the rail. They don’t usually have a tapered profile, but a flat or V-shaped one, depending on the application. In a double flanged wheel, it is important to find a tread size compatible with the rail size. The double flange should be able to manage small dislocations in the rail and debris on the track.
What inner diameter do I need for the wheel bore?
A wheel’s bore is the hole in the center of the wheel where the axle is placed.
The inner diameter of the bore is where the axle fits. Check with your engineer about the right size bore for your axle: tolerance is important and can vary depending on use. What is appropriate in a hot kiln may not be the same as what’s appropriate in a freezer.
Do I need a bushing?
Bushings are a sleeve that fits snugly inside a wheel’s bore and decreases friction in the wheel and axle system. Since bushings can be replaced, they help prevent wear of the wheel, and sometimes extend the wheel’s working life. However, other times, they are there simply for their mechanical effect.
Bushings work differently than bearings, the other common fitting for a wheel bore; a bushing works with the axle sliding along the surface, whereas a bearing uses small rotating cylinders or spheres to lower friction.
When choosing a bushing, inner diameter (ID), outer diameter (OD) and tolerance are important engineering details. The bushing’s outer diameter needs to fit snugly within the diameter of the wheel’s bore. The inner diameter describes the diameter of the hole in the center of the bushing. Tolerance is how much precision is needed in these measurements for the requirements of the application. Mechanical systems can all vary widely with what they need, based on the environment and load, and so these requests need to be precise during order.
Bushings can be put in before shipping or shipped separately to be installed by engineers on site.
Read more about bushings: Do You Need Bearings or Bushings for Your Wheel?
Bronze bushings vs. nylon bushings: which will work for me?
Many types of bushings are commercially available. In industrial wheels, bronze bushings (sintered or cast) and nylon bushings are most common.
Nylon bushings are inexpensive, lower friction, and stand up well to the sliding movement of loads. They may contain a lubricant in the material itself (as with Nyloil bushings). Bronze bushings, especially cast bronze, are used in applications with very heavy loads. Sintered bronze, usually impregnated with oil, offer a bit of both worlds.
Do I need a lubricant?
Some bushings are used without lubricant. Bronze bushings are often chosen because bronze is a metal that resists galling—the tendency of metals that are sliding together in close contact to abrade each other, causing material to pill or pile between them.
Some bushings (like Nyloil bushings or sintered bronze) have lubricant built into them, so that as they wear, oil is released.
For other applications, oil is needed to ensure smooth functioning. In these situations, a wheel that contains a “zerk” or “nipple” is needed: this small hole in the bore allows oil to be fed in. Some bushings come with a zerk and grease channel, but often these wheels are used without bushings.
Industrial track wheels are an excellent solution for many storage and manufacturing applications. Our low-RPM wheel solutions are available in both stock and custom options. Knowing what your application needs is important for the safety and efficiency of your plant, so speak to an engineer to make sure you’re ordering exactly what you need!
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