Today, you’ll learn about top plates and some prevalent sizes used in the industry. The aim here is to provide advice that’s brief and straightforward, focusing on three series of casters that cater to a wide array of common applications in the industry. Let’s start with the basics. A top plate is a square or rectangle plate on top of the caster, featuring 4 drilled bolt holes. These holes allow for screws/bolts to be inserted, meeting a nut and affixing the caster to the surface it’s meant for. Although it is commonplace in the industry, top plates come in a vast range of sizes, often leading to confusion and errors when replacing old casters. Below, you’ll find an evaluation of some standard sizes, alongside some common alternatives to give a better understanding of the available options in each of the three series.
General/Light Duty Caster Series
For the General/Light Duty caster series, it’s worth mentioning that this can be the most confusing series of top plates. Numerous sizes tend to fluctuate with wheel size, and there’s a noticeable shift from swivel to rigid casters. A prevalent top plate size in this series is the 1-7/8” x 2-9/16” top plate with a bolt hole pattern of 15/16” x 2-1/8”. Another similar size is the 3-1/8” x 4-1/8” with a bolt hole pattern of 2-3/8” x 3-3/8”. As mentioned, this series often changes plate sizes as the wheel size increases. Some common correlations are listed below:
2” Wheel – 1-7/8” x 2-9/16”
2-1/2” Wheel – 2-3/4” x 3-7/8”
3” Wheel – 3-1/8” x 4-1/8”
4’ Wheel – 4” x 5”
Most wheels in this General/Light Duty series tend to be about 7/8” or 15/16” wide. Given the variability in top plate sizes in this series, it might be wise to call a trained caster professional to assist in finding the right size for your needs.
Light Duty/Institutional Casters
In the Light Duty/Institutional casters series, things are more straightforward. The industry commonly uses a top plate size of 2-3/8″ x 3-5/8″ with a bolt hole pattern of 1-3/4″ x 2-7/8″, slotted to 3″. Although the industry lacks a true “standard”, we can consider this a typical size for this series. Another frequently chosen option in this series is a 3-1/8” x 4-1/8” top plate, which has a bolt hole pattern of 1-3/4” x 2-15/16” and is slotted to 2-3/8” x 3-3/8”. Most wheels in this series would be 1-1/4” wide.
Medium/Heavy Duty Casters
This next entry will cover the Medium/Heavy Duty caster series as the last series. This series mirrors the simplicity of the light duty/institutional series. In this series, the top plate of 4” x 4-1/2” with a bolt hole pattern of 2-5/8” x 3-5/8” slotted to 3” x 3” is the most common size. A common alternative would be the 5” x 5-1/2” top plate with a bolt hole pattern of 4-1/8” x 4-1/2”.
Having covered some of the most common top plate sizes, hopefully, you now have a better understanding of how to identify your top plate and what to look for in a replacement. It can be incredibly frustrating to order a caster, only to discover the top plate size is incorrect. If you are having trouble identifying the right top plate size, or if you have any other questions, don’t hesitate to reach out to our team of experts for guidance on choosing the correct caster for you!
