Castors Fitting Types
Top Plate fitting castors - This is the most common castor. It is the most robust form of fitting a castor to an application. The plate will usually have 4 holes around the top plate. Ideally all four holes should be used to fix the castor but in some cases it may only be possible to use three of the castor holes. The castor plates are usually rectangular but on some of the lighter duty castors they may be square plates. Standard hole centres for European castors are placed at either 80mm x 60mm or 105mm x 80mm on larger castors.
The extra heavy castors may have plates larger than this and bolt hole centres will also vary.
Bolt Hole fitting castors
A circular metal plate castor with a single fixing hole built for a fixing bolt. This type of fitting is used best where castors are to be fitted to legs of furniture or trolleys. The castors can be fitted by either pushing a bolt up from underneath or a bolt down and a nut fitted. Some applications have spigots fitted and bolt hole castors can be fitted to the spigots.
These castors can also be used with expanders. Expander castors use a device fitted to the castor that when pushed inside a tube will expand and cause a friction fit between the expander and the tube. This should be strong enough to hold the castor in place.