Last updated 2026-11-12
Caster Mounting Types: Stem, Top Plate and Bolt Hole Guide
Compare threaded stem, grip-ring, top plate and bolt hole casters. Learn how to measure stem size, plate holes and mounting height for replacement.
Choosing the right caster mounting types starts with the equipment frame, not the wheel colour or diameter. A caster can have the correct load rating and still be impossible to install because the thread, tube fit, plate holes or overall height is wrong. Use this guide to compare threaded stem, grip-ring, top plate and bolt hole casters and measure an existing unit for replacement.
Quick answer: the four main caster mounting types
| Mounting | How it attaches | Measure first | Typical JLS family |
|---|---|---|---|
| Threaded stem | Screws into a matching nut or threaded fitting | Thread diameter, pitch and usable length | S series |
| Grip-ring / expanding stem | Retained inside a tube or socket | Tube inside diameter, wall and insertion depth | C series |
| Top plate | Bolts through a flat plate | Plate dimensions, hole centres and bolt size | D series |
| Top hole / bolt hole | Uses a central hole through the swivel assembly | Hole diameter, bolt and frame clearance | K series |
The series letter is only a starting point. Confirm the exact SKU and drawing before ordering, because frame geometry, load and brake choice still matter.
Threaded stem casters
Threaded stem casters attach to a matching nut or threaded fitting in the equipment. They are common on tubular frames, workbenches, displays and equipment where a compact connection is preferred.
To learn how to measure caster stem size, record three separate dimensions: the thread outside diameter, thread pitch and usable stem length. A diameter match is not enough; two stems with the same diameter can have different pitches and will not thread together correctly. Check whether the existing fitting is a nut, threaded insert or tube socket and whether any thread remains engaged after the caster is seated.
JLS examples include JLS-3-SH TPR casters for equipment and medical carts, JLS-3-SZH PP casters for warehouse trolleys, and JLS-3-SBPU PU casters for workshop and logistics use. Compare each model's stated stem and overall-height drawing with the old unit.
Grip-ring and expanding stem casters
Grip-ring and expanding stem casters fit into a tube or socket. A grip-ring design is retained by the ring's grip against the tube, while an expanding stem uses an expansion mechanism to secure the fit. The exact mechanism must be confirmed rather than treating every smooth stem as interchangeable.
For these mountings, the tube's inside diameter is usually more useful than its outside diameter. Also record tube wall thickness, insertion depth and any deformation or corrosion. Measuring only the outside of the tube can lead to a loose fit or a stem that cannot be inserted.
The JLS-3-CH grip-ring / expanding stem caster is an example from the JLS range. Provide the tube's internal measurement and clear photos of the old stem and socket when checking compatibility.
Top plate casters
Top plate casters attach with multiple bolts through a flat plate. They are widely used on equipment bases, workbenches, cabinets and frames that provide a flat, adequately supported mounting surface.
Measure caster top plate dimensions and the hole pattern separately: overall plate length and width, centre-to-centre spacing in both directions, hole diameter and the bolt size used by the frame. Two plates with the same outside dimensions can have different hole centres. Also check that the frame provides enough room for a wrench and that the bolts do not project into nearby components.
JLS-3-DBP top plate casters are one JLS example. Match the product drawing to the actual frame rather than assuming a similar plate outline proves a fit.
Top hole and bolt hole casters
Top hole or bolt hole casters use a central hole through the swivel assembly instead of a multi-hole plate. They are useful on compatible OEM frames where a central bolt connection is required.
Record the hole diameter, bolt specification, frame thickness and the space available above and around the swivel. Check how the connection is secured and how rotation is managed. A central hole that accepts the bolt is only one part of compatibility; the bracket, fastener and frame must work together as an assembly.
JLS examples include JLS-3-KCH PP top-hole casters and JLS-3-KH TPR top-hole casters. Their different tread and brake options do not change the need to verify the central connection and clearance.
Mounting height and swivel radius
Caster mounting height is the vertical dimension from the equipment's mounting contact surface to the floor under a defined measurement condition. It is not the same as wheel diameter. A replacement with a different overall height can change equipment level, working height and load distribution.
Swivel radius describes the space the caster needs to rotate around its swivel axis. Check the wheel, fork and brake through the full turn, not just with the caster pointing forward. A caster that bolts on correctly can still hit the frame, adjacent wheels or nearby components when it swivels.
Use the product's 2D drawing to compare overall height and clearance. Measure the old equipment on a repeatable, level setup and note whether it is empty or loaded so the comparison is meaningful.
How to replace a caster in six steps
- Identify the mounting: photograph the old caster, frame and fastener from several angles.
- Measure the interface: record thread, tube, plate or central-hole dimensions using the appropriate method above.
- Measure the geometry: record mounting height and the available swivel and brake clearance.
- Calculate the load: include equipment, payload and accessories using the caster load capacity guide.
- Select the working features: compare TPR, PU and PP tread options, bearings and brake requirements.
- Verify before volume: compare the 2D drawing and, where necessary, approve a sample before placing the full order.
For a broader selection process, use the 7-step caster selection guide before confirming the final model.
Common mounting mistakes
- Measuring tube outside diameter when the stem requires the internal fit.
- Checking thread diameter but forgetting pitch or usable length.
- Comparing plate outline without checking hole centres and bolt clearance.
- Assuming a central bolt hole is interchangeable with a multi-hole plate.
- Ignoring overall height, brake position and full swivel clearance.
- Ordering by wheel diameter or colour without checking the exact mounting drawing.
Product selection and buyer checklist
Before requesting a replacement quote, prepare the old mounting type, clear photos, thread or tube measurements, plate or central-hole dimensions, mounting height, available swivel space, total operating weight, floor condition and brake preference. This information lets the supplier narrow the compatible models before price is discussed.
Browse the JLS caster catalogue for the four mounting families, or send your old-caster photos and dimensions for a matching model, drawing and quote.
Frequently asked questions
What are the main types of caster mountings?
The four common mounting types are threaded stem, grip-ring or expanding stem, top plate, and top hole or bolt hole. The right choice depends on the equipment frame and the dimensions of the existing connection.
How do you measure a threaded caster stem?
Measure the thread outside diameter, thread pitch and usable stem length. Also record the mounting height and the socket or nut arrangement. Diameter alone does not confirm compatibility because the same diameter can have different pitches.
What is the difference between grip-ring and threaded stem casters?
A grip-ring or expanding stem is retained inside a tube or socket, while a threaded stem screws into a matching nut or threaded fitting. Check the tube's internal dimensions and the actual stem mechanism before substituting one for the other.
What is the difference between top plate and bolt hole casters?
A top plate caster fastens through several holes in a flat plate, while a bolt hole or top hole caster uses a central hole through the swivel assembly. Their hole patterns and frame interfaces are not directly interchangeable.
How do you measure caster mounting height?
Measure from the equipment's mounting contact surface to the floor with the equipment in a defined, repeatable condition. Compare this with the product drawing's stated overall height and check the available swivel clearance separately.
Can I replace a stem caster with a top plate caster?
Only after reviewing the frame, attachment method, mounting height and connection strength. A suitable plate and bolting surface must exist or be engineered; changing the mounting type should not be treated as a simple wheel swap.
Zehong Dong — Technical sales manager, JIELISHI
Handles OEM and distribution enquiries for casters — load and mounting selection, sample approval, custom tooling and the production follow-up in between.