How to Use the Thomson Linear Actuator Manual and Catalog: A Six-Step Procurement Checklist

If you've ever opened a newly delivered actuator box and found the wrong mounting flange, you know that specific sinking feeling. I'm the office administrator for a 40-person automation components company, which means I manage roughly $1.2M in annual component spend across eight vendors. Thomson Linear is one of the names that keeps showing up in actuator and motor specs. Because I report to both operations and finance, I care about two things: the part not failing in the field and the invoice not getting rejected. Over the last five years, I've turned our ordering process into a checklist. This is the six-step version I use whenever someone says 'thomson-linear' in a product review.

This checklist is for engineers who have to specify a linear motion system and for buyers who have to turn that spec into a PO without creating a field failure. Step 4 is the one most people skip.

Step 1: Open the thomson linear actuator manual before you touch the catalog

The conventional wisdom is to start with the Thomson Linear actuator catalog, find a part number that looks close, and only open the manual if you need installation dimensions. That's backwards.

The catalog is a comparison tool. The manual is the safety and performance document. The manual tells you duty cycle, IP rating, thermal limits, mounting requirements, and lubrication intervals. It also has wiring diagrams and emergency stop notes. If you're not looking at those, you're not ready to specify.

When I took over purchasing in 2020, I ordered an actuator based on stroke length and load capacity. Good spec, wrong duty cycle. The actuator was rated for 10% duty, and our application ran almost continuously. It overheated in about three months. The manual had the duty cycle table on page 14 (page 14, I know). I just didn't open it.

Checkpoint: Download the manual for the product family before you search the catalog. If the duty cycle or IP rating doesn't match your application, stop and change your selection.

Step 2: Use the Thomson Linear actuator catalog for exact part numbers

The thomson linear actuator catalog is actually pretty good once you know what to look for. The part number structure is the language your supplier uses to build the right unit. Stroke, voltage, feedback, gearbox ratio, connector orientation, and mounting option all matter. Each part of the number matters.

I've seen buyers try to shorten part numbers to save cost or avoid confusion. That's how you end up with a standard-duty actuator instead of a heavy-duty unit, or a 24 VDC version instead of 230 VAC. The catalog isn't there to make your life hard. It's there to make the factory produce exactly what you need.

Keep the revision date of the catalog too. The manual lists which lubrication and maintenance the actuator needs. If your maintenance schedule can't support that, the product number may need to change.

Checkpoint: Write down the entire part number. Every digit. If an option in the catalog is unclear, find it in the manual or call support before you issue the PO.

Step 3: Know whether you need an induction motor or a high torque servo motor

If the actuator is part of a positioning system, the motor choice usually comes down to an induction motor or a high torque servo motor. These are not interchangeable.

Induction motors are simple, robust, and relatively inexpensive. They run at nearly constant speed when connected straight to line power. If you need speed variation, you add a VFD. A high torque servo motor is a closed-loop machine: it uses encoder or resolver feedback, produces high peak torque, and can accelerate and decelerate quickly. For a Thomson Linear ball screw actuator, a servo motor makes sense when you need repeatable positioning and precise velocity control. An induction motor with a VFD makes sense when you need lower cost and don't need precision.

Torque alone doesn't tell you whether the motor can deliver that torque at the speed your actuator needs. A high torque servo motor has a different continuous torque curve than an induction motor, so comparing only peak numbers is misleading.

The 'just use a bigger motor' thinking comes from an era when servos were expensive and hard to tune. That has changed. A correctly sized high torque servo motor can do what a much larger induction motor does, with less inertia and better control.

When I compared orders that specified the motor family correctly against ones that didn't, the difference wasn't just unit price. It was commissioning hours, spare parts, and phone calls from frustrated maintenance teams.

Checkpoint: Verify which motor family the application requires before comparing torque ratings.

Step 4: Understand how VFD control motor speed works and check the motor rating

If you've ever searched for 'how vfd control motor speed,' you've probably seen a long explanation about V/f ratios. Here's the plain-language version: a variable frequency drive changes the frequency of the power supplied to the motor. Speed follows frequency. In the synchronous speed formula, N = 120 x f / p. A 4-pole induction motor at 60 Hz has a synchronous speed of 1,800 rpm. At 30 Hz, it's 900 rpm. The VFD also adjusts voltage along with frequency so the motor doesn't saturate.

Per NEMA MG 1, a general-purpose motor is not automatically rated for inverter-fed operation. If the application needs speed control below the motor's rated speed, specify an inverter-rated motor.

This is the step most people skip. A standard induction motor running at low speed on a VFD can overheat because its cooling fan is turning slower while the load still demands torque. The spec needs to say 'inverter-rated' or 'vector-duty,' and the VFD parameters should be set to match the motor nameplate. A VFD also controls acceleration and deceleration, which can reduce shock to the actuator. But that only works if the drive is sized and programmed correctly.

I learned this the hard way in our 2024 vendor consolidation project. We ordered a motor that matched the VFD, but the motor wasn't rated for continuous low-speed duty. Bench tests looked fine. On the customer's floor, the motor tripped on thermal overload after 45 minutes. The surprise wasn't the failure. It was how small the price difference was for an inverter-rated motor.

Checkpoint: If your system uses a VFD, check the motor nameplate or datasheet for inverter-rated / NEMA MG 1 Part 31 before approving the order.

Step 5: Verify the mechanical interface before you send the PO

Once you have the actuator part number and motor family, you still need to connect them. Gearbox, coupling, flange, shaft key, cable length, and mounting orientation all need to be compatible.

The actuator manual usually includes the allowable input torque and mounting position. If your selected motor exceeds that input limit, you need a gearbox or a different actuator. That's a spec detail, not a minor adjustment. I've seen orders where the motor and actuator were both correct, but the coupling between them was an afterthought. That costs more than the part. It costs engineering time, freight, and the credibility of your delivery date.

Here's where the quality perception piece comes in. The last 10% of a spec—the coupling, the bracket, the cable strain relief—is what the customer's maintenance team actually touches. If that part feels cheap, the whole machine feels cheap. A $50 difference at the component level can turn into a $5,000 callback.

Checkpoint: Confirm the mechanical interface and cable options are in the order, not added later.

Step 6: Build a one-page cross-reference sheet

From a purchasing perspective, this is the step that separates smooth projects from chaos. After you've specified all the parts, write down the full product number, description, quantity, and the manual or catalog revision you used. If someone asks, 'why this part?' you can point to the source instead of relying on memory.

In our 2024 consolidation project, a one-page cross-reference sheet cut our order review time from about six hours down to under two. It also eliminated the problem of ordering the same part number from two different vendors with different revision levels. The sheet also helps finance: when an invoice doesn't match the PO, they can quickly see whether the difference is a legitimate option or a pricing error.

Checkpoint: Before sending the PO, make sure the BOM includes the actuator part number, motor part number, VFD model (if needed), and the manual revision date.

Final notes: what to avoid

• Don't order from the catalog without checking the duty cycle and IP rating in the manual.
• Don't assume every induction motor can run on a VFD at low speed. Check for inverter-rated insulation and cooling.
• Don't replace a servo motor with an induction motor just because the torque numbers look similar.
• Don't let a missing coupling or bracket turn a well-specified system into a field failure.
• Keep a version record. The Thomson Linear manual and catalog are updated for a reason.

I'm not an engineer. But after five years of ordering and replacing these components, I know that the quality of a spec shows up on the customer floor. The manual-first process gets the details right, and the details are what make the system last.