Although often overlooked as a critical part of any mobile scaffold, Wheels are an integral part of the structure, and need to be looked after in the same way. There are quite a variety of scaffold wheels available on the Australian market, which is right for your scaffold?
Wheel or Caster (Castor)
Caster is a description of the device structure used to hold the wheel, and is not an important delineation in the selection process for a mobile scaffold. The information below applies equally to wheels and Casters, to keep things simple we will use the term wheel for all devices.
Wheel Diameter
130mm (5 inch) wheels are generally for the smaller end of the light duty range of scaffolds, they invariably have no adjustment, and will include a locking pin to secure them to the scaffold frame. All Scaffolding wheels should have a brake mechanism that is robust and able to be operated using your boot. The smaller diameter wheels are not favoured for heavier and taller mobile scaffolds due to the reduced ability to deal with debris and variations in surface conditions. This could cause the wheel to catch and may in some circumstances produce instability or cause the scaffold to tip.
200mm (8 inch) wheels are well suited to larger and taller mobile scaffolds, due to the ability of the wheel circumference to ride more readily over rough surfaces and possible debris. The arrangement of the wheel in relation to the load, placing it more directly under the tube fitting, transmits the weight in a straighter line to the supporting surface. All Scaffold wheels should have a robust and easily operated brake mechanism.
Safe Working Load (SWL)
Mobile Scaffold wheels must be tested for SWL, and most will have that information marked in some way on the body of the wheel. Five inch wheels are generally for use with Light Duty Scaffolds(225kg SWL) and eight inch wheels are generally for use with Medium Duty Scaffolding (450kg SWL). Load capacities on wheels vary greatly across manufacturers, check this before purchase.
Tube Compatibility
Each Mobile Scaffold wheel is designed to match up with a specific tube diameter where it marries with the mobile scaffold frame. This is a critical part of the wheel selection, as choosing a wheel that does not meet correctly with your scaffold frame may cause wear, cracking or in severe cases instability. Check the recommended tube diameter for the wheel you are considering before purchase. Tube sizes may be described as ID (Inside Diameter) or OD (Outside Diameter) depending on the tube.
Adjustment Shaft
Where a scaffold wheel includes a thread and nut to provide vertical adjustment, it is important to understand the limits of that adjustment, and the shaft length. Some wheels come with a shaft that is threaded for its’ entire length, and others are limited to two thirds of the shaft length. Regardless of the physical arrangement, it is not safe to operate a scaffold with the more than two thirds of the shaft length outside the frame of the mobile scaffold, and it is not recommended to use more than half of the shaft length. If your chosen mobile scaffold wheel has a 600mm shaft, we recommend that you do not adjust the nut any further than 300mm from the top of the wheel housing.
Wheel Covering
Rubber and Polyurethane are the popular choices for wheel coverings amongst most manufacturers. Rubber is often preferred for the 5 inch wheels, whereas Polyurethane is common for the larger sizes. Polyurethane is generally harder wearing, and with thinner application it tends to deform less under heavier loads. Both are perfectly acceptable up to the SWL of the wheel.
Questions
If you have questions about wheels, or any other scaffolding components, please don’t hesitate to call the Mr Scaffold team on 1300 677 223.