About Wheels and Castors
• Overview Wheels and Castors
• Castor Selection Criteria
• Load Capacity
• Wheel Diameter
• Bearings
• Castor Fitting Types
• Castor Housing Types
• What to do next ?
A castor is a wheel mounted to a Housing but has an additional offset swiveling Bearing Race. The Bearing Race (Bearing Head) allows the wheel to rotate freely in 360°. This allows for easy turning of objects without changing the direction of the chassis to which the castors are mounted. The angle and distance of the wheel axles and Bearing Race can be adjusted for different types of castor performance. Castors also come with Rigid Housing which will maintain one direction.
Castors are typically used on Material Handling Applications and Trolleys and are normally mounted underneath.
During straightforward motion, the swivel caster will tend to rotate parallel to the direction of travel. This can be seen on a shopping cart when the castor rotates backwards during forward motion down an aisle. A benefit of this castor rotation is that the vehicle naturally tends to travel in a straight direction. Precise steering is not required because the casters tend to maintain straight forward motion.
This is also true during turning. The castor rotates, again parallel to the turning radius, and provides a smooth turn. This can be seen on a shopping cart, as the wheels rotate differently depending on how tight a turn is made.
Castors can be designed in many different sizes and materials depending on application. They can be made from Nylon Castor Wheels, Polyurethane Tyred Nylon centre Castor Wheels, Grey Rubber Castor Wheels, Grey Rubber Tyred Steel centre castor Wheels, Aluminium centre Black Elastic Rubber Tyred Castor Wheels, Black Rubber Tyre Steel Castor Wheels, Blue Elastic Rubber Castor Wheels, Cast Iron Centre Polyurethane tyred Castor Wheels, Cast Iron Castor Wheels, High Temperature Castor Wheels, Aluminium centre Polyurethane tyred Castor Wheels, Pneumatic Tyred Castor Wheels, Solid Rubber Castor Wheels. Castor Housing can be made from Zinc Plated Mild Steel, Stainless Steel and Plastic.
Castor Selection Criteria
Load Capacity
Load Capacity are calculated in two methods depend on the anticipated type of load. First establish if the loads are Liquid or Solid then apply the following:
Liquid Loads: If the load consist of liquids our calculation considers that the load can move and could be over just two castors at one time:
Weight of Application including TrolleyLoad capacity of castor = ---------------------------------------------------------- 2
Solid Loads: Working to the principle that the application might not be parallel with the ground if the ground surface is uneven then only three castors will be supporting the load.
Weight of Application including Trolley Load capacity of castor = ---------------------------------------------------------- 3
Wheel Diameter
The basic principle to work to is that the Larger the wheel diameter the less resistance it requires to move and therefore a consideration at the design stage for any application using castors, if regular movement is required.
Before Selecting a wheel it is important to determine if the wheel material is compatible with the chemical environmental conditions, the temperature and humidity, all of which effect the wheels operation.
Wheels are available in a large variety of materials all of which are suitable for different environments and working condition. Basic Principles applied: The Harder a Wheel Tread the Easier the wheel will move and the less resistance to start motion. The Strongest wheel are Steel Wheels which will carry the highest loads and with-standard the worst condition however they will damage floors and be noisy.
1. Nylon Wheels offer the cheapest solution for a standard wheel, however liable to skid if obstructed buy small objects on the floor.
2. Polyurethane tyred wheels with Nylon Centres are a good all round wheel they carry good loads, will not mark or damage floors.
3. Grey Rubber Castor Wheels with Plastic Centres offer a non marking light weight solution general material handling application.
4. Grey Rubber Tyred Steel centre castor Wheels offer a non marking light weight solution general material handling application the steel centre enables the wheel to handle higher shock impact loads.
5. Aluminium centre Black Elastic Rubber Tyred Castor Wheels the elastic rubber enables with wheel to carry high weight loads whilst the Aluminium centre will dissipate the heat from the bore with greater ease.
6. Black Rubber Tyre Steel Castor Wheels offer a light weight solution general material handling application the steel centre enables the wheel to handle higher shock impact loads.
7.Blue Elastic Rubber Castor Wheels this is a non marking elastic rubber which improves the load rating of the wheel.
8. Cast Iron Centre Polyurethane tyred Castor Wheels this is the most common wheel used in heavy duty applications the polyurethane offer high load capacity and the cast iron core with Ball Bearing bore offers a robust core to handle the loads.
9. Cast Iron Castor Wheels very strong wheels which work well in hard condition where some temperature could be involved for example a powered coaters
10. High Temperature Resin Castor Wheels a perfect solution where the wheels need to with standard high temperatures for periods of time most commonly found in Bakeries.
11. Aluminium centre Polyurethane tyred Castor Wheels this is the most company wheel used in heavy duty applications the polyurethane offer high load capacity and the Aluminium core will dissipate the heat build up better, this wheel offers a lighter unit weight compared to the cast iron core. Important if you forward applications via couriers.
12.Pneumatic Tyred Castor Wheels a great solution if your application needs to work over rough terrain. Available with a Plastic Centre or Painted Steel Centre
13. Solid Rubber Castor Wheels standard Trolley wheels used in many applications offer reasonable weight loads and large wheel diameter. Available with a Plastic Centre of Painted Steel Centre
Ensure you seek advise from Coldene Castors before ordering if you have any concerns sales@coldene.co.uk 01327 350070
Bearings Plain Bore Normally part of the moulded wheel or a nylon bush may have been inserted so the wheel will run directly on a shaft or axle.
Needle Roller Bearings A cage holds steel roller together (needles) this will be found in the bore of wheel measure as the final required bore. Needle roller bearings will reduce friction between the axle or shaft and the wheel.
Ball Bearings Precision Steel Balls encapsulated in a steel cage will reduce the friction between the wheel and axle of shaft – best suited for very high loads
Castors Fitting Type
Castors can be fitted to Applications in several different ways:
• Top Plate Fitting the most common type, this is where the castor has four holes on a mounting plate enabling the castor to be bolted or screwed to an application
Example of a Top Plate Castor: Click Here
• Bolt Hole Fitting: enabling a bolt or expander to be used to secure the castors to the Application.
Example of a Bolt Hole Castor: Click Here
Castor Housings Types
Castors come in three main types:
Top Plate Swivel Castors: Four Hole Fixing Points on a Mounting Plate this Style of Castor will Swivel 360 degrees.
Example of a Top plate Swivel Castor: Click Here
Top Plate Swivel Braked Castors: Four Hole Fixing Points on a Mounting Plate this Style of Castor will Swivel 360 degrees complete with a locking system to brake the Wheel and the Swivel Motion
Example of a Top Plate Swivel Braked Castor: Click Here
Top Plate Fixed Castors: Four Hole Fixing Points on a Mounting Plate this Style of Castor is Rigid and will only travel in one direction.
Example of a Fixed Top plate Castor: Click Here
Top Plate Swivel Directional Lock Castors: Four Hole Fixing Points on a Mounting Plate this Style of Castor will Swivel 360 degrees complete with a Directional locking system which enables the directional of travel to be locked into one position (this does not lock the wheel)
Top Plate Swivel Directional Lock Braked Castors: Four Hole Fixing Points on a Mounting Plate this Style of Castor will Swivel 360 degrees complete with a Directional locking system which enables the directional of travel to be locked into one position complete with a locking system to brake the Wheel and the Swivel Action.
Example of a Swivel Brake with Directional Lock: Click Here
Bolt Hole Castors: Single Fixing Point Bolt Hole Castors will Swivel 360 degrees.
Example of a Bolt Hole Castor: Click Here
Bolt Hole Braked Castors:Single Fixing Point Bolt Hole Braked Castors will Swivel 360 degrees and Brake the Wheel and Swivel Action
Example of a Bolt Hole Braked Castor: Click Here
It is worthwhile remembering that you may need a fixing kit to secure your castors to the necessary application. These can be found here. They can be attached alternatively, by either using an expander, Expanders are attached to bolt hole castors and are pushed into a hollow tube and tightened till they exand and hold the castor in place. Alternatively you can use a Threaded Stem and attach it via a Threaded Insert or a Weld Plate
What do you want to do next ?
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