If you’ve ever sat in an office chair or used a cart at a hardware store, you know how useful ball casters can be. Ball casters provide pivot points to allow wheels to move in all four directions. Casters increase the range of motion, so they play a pivotal role in material handling applications. 

Most people have used them before, but how do ball casters work? Casters seem straightforward but contain several parts working together to produce a smooth motion. The team at Caster Central put together this article about ball caster operation and applications. 

Contact us today for more information about our reliable ball casters!

Ball Casters vs. Traditional Casters

Every type of caster is different, but virtually all casters contain three core components: 

• Top Plate: The top plate is the part that connects to whatever equipment the casters are for. Top plates are usually rectangular and connect to equipment with screws in each corner.
• Fork: The fork is the middle part of the assembly and connects to the wheel below and the top plate above. Forks are usually U-shaped brackets with holes in the ends that connect to the wheel axle. Other names for forks include yoke, horn, rig, and legs. 
• Wheel: The wheel is self-explanatory and allows the equipment to roll. It connects to the fork and makes contact with the ground. Most caster wheels use metal or some kind of heavy-duty thermoplastic. 

Basic caster design is extremely simple, but manufacturers have tens of thousands of casters that modify or add to these main parts. This simple design provides smooth rolling motion for a wide range of equipment applications. 

Ball casters modify this design; instead of a wheel, ball casters use a single sphere that mounts in a recessed spherical housing. The housing contains ball bearings that allow the sphere to rotate freely in any direction. This design differs from traditional casters, where the wheel can only spin on its single axis. 

As such, ball casters are usually smaller than traditional casters and are more common in applications that require precise motion and positioning. They provide a wider range of motion than rigid casters and more control than swivel casters. 

Types of Ball Casters 

There are two main types of ball casters. 

1. Flange-mount: ball casters have flared edges with holes. Screws go through these holes to attach the caster to equipment. Flange ball casters are the most common and least expensive type. 
2. Stem-mount: ball casters have a single screw that mounts in a hole on the bottom of the equipment. Additionally, stem-mount ball casters provide smoother motion because you can place them closer together. 

Benefits of Ball Casters

So, how do ball casters work? Quite well, actually! Ball casters have some notable benefits compared to traditional metal casters. 

Omni-Directional Motion

Swivel casters are more mobile than rigid casters, but they still have some noticeable limitations. Ball casters provide even more movement freedom as you don't have to rotate the raceway to change the direction of motion.

Precise Motion

Ball casters’ smaller profile and rotation surface mean they are capable of more precise movement than typical swivel or rigid casters. Axles lock swivel caster wheels into a single axis of motion, while ball casters can rotate in virtually any direction. 

Additionally, you can place ball casters closer together than swivel or rigid casters, providing more friction and control on the rolling surface. Most ball casters have a high diameter to weight ratio to move over obstacles. 

Easy to Install

Both stem and flange-mount casters are easy to install on various applications. They generally have fewer mounting points, and their smaller size makes them easier to work with. Ball casters are also lightweight.

Durable

With traditional casters, the wheel axle and kingpin absorb the brunt of the downward force, creating stress points. Ball casters distribute downward forces more evenly across the top of the sphere, providing a more stable rotation compared to other casters. 

The result is that ball casters are more durable relative to their size than traditional casters. This relative durability makes them ideal for smaller heavy loads. 

Ball Caster Applications

You can use ball casters for various applications, including: 

Conveyor Belts

Conveyor and assembly belts make heavy use of ball casters thanks to their capacity for omni-directional motion. Often, manufacturers use face-up ball casters to provide a rolling surface they can quickly move items across. 

Other times, manufacturers use ball casters to allow low-profile smooth motion down conveyor lines. Conveyor ball casters are for industrial applications, so they are typically steel and have very high weight capacities.  

Robotics

Various mobile robotic applications incorporate ball casters for additional motion control. Many robots use ball casters as a third "wheel" to help with steering while back wheels handle locomotion. Ball casters are particularly useful for smaller robots that are too heavy for traditional casters. 

Furniture

Ball casters are also common fixtures on furniture to help movement. Ball casters give furniture lower clearance from the floor and are less destructive to certain types of floors. Common furniture with ball casters includes dressers, office chairs, cabinets, ottomans, armchairs, and coffee tables. 

Ball Caster FAQ

Below are some of the most common questions we receive about how ball casters work. 

How Are Ball Casters Different from Wheels?

Ball casters do not have a single axis of rotation, unlike traditional caster wheels. This design feature gives them a wider range of motion.

What Is the Best Material for Ball Casters?

Stainless steel is one of the most common materials for ball casters, as well as zinc, aluminum, and titanium. 

Are Ball Casters Better Than Swivel Casters?

Ball casters generally provide more precise motion than swivel casters and are better for smaller applications. Swivel casters are usually better for larger applications that don’t require as much precision with motion. 

For more answers to "How do ball casters work" or to learn how to choose the best caster for the type of use, contact Caster Central at (800) 445-4082.