7" Diameter Cast Iron Wheels
Wheel patterns must be manufactured with the same machine set-up as used for the track to assure a mirrored fit. The chemical composition of the cast wheels is slightly softer than the track, therefore the wheels will wear and protect the imbedded track.When using the "switch system" of track design (versus "turntable system"), wheel diameter is crucial. The 7" wheel diameter is inherent to the standard switch design. As the wheel moves over the raised transition areas, not only should the wheel raise clear of impact points, the wheel diameter must be large enough to straddle the intersection gap or damage will occur at the impact points.Switch levers, manufactured of steel or not precision cast to the exact track curvature will act as a "whetstone" on cast iron wheel flanges. These "sharpened" wheels will in-tum damage your imbedded track, significantly reducing its life expectancy.Steel wheels on a cast iron track will accelerate the wear of the imbedded track. The inherent system design is to have the wheels wear instead of the imbedded track, since wheels are easily replaced.
REPLACING WORN WHEELS IS THE SINGLE MOST IMPORTANT REQUIREMENT NECESSARY TO PROTECT THE IMBEDDED TRACK SYSTEM.
A) Raised transition allows wheels to ride on the flange.
The 7" diameter wheel riding surface is lifted clear of track impact
points and should be 9/16" deep, examine for wear with a straight edge and
rule. See drawing Note "A".
A) Worn transition area - typical, inherent in design
B) Worn flange radius and worn flange - typical, due to wheel wear. The system is designed to allow the wheels to wear in order to protect imbedded track.
Wheel replacement is dictated by observance of wear as previously mentioned. It is not possible to estimate years of wheel service, due to the uniqueness of each facility and the quantity of dollies in service. Maintenance goals are to protect the imbedded track by replacement of low cost, easily replaced, components.
Most common causes of track deterioration:
1) Poor quality wheel castings with sharp edges and rough ground flange radii.
2) Worn wheel flanges creating sharp edges instead of gentle radius contact.
3) Poor quality bearings, if you have old needle style bearings you can be assured your
wheels need replaced. Technological advancement in bearing designs have made the
needle bearings obsolete and dual roller type (two per wheel) should be used.
4) Using dollies from other facilities, Non-OEM wheels, etc.
5) Steel Switch Levers.
6) Steel Wheels.
7) Nothing will "take-out" a track system faster than improper wheels.
© 2001 Capital Track Co.