Will the Load Force Double if Two Linear Motors Are Connected in Series?

This is a classic and important question. In short: theoretically, under ideal conditions, "mechanically connecting" two identical linear stepper motors in series to push the same load would double the output force. However, in practical engineering, this is generally a poor design choice fraught with significant risks and is not recommended.

Our commercially available linear motors have a maximum thrust capacity of 2400N. Connecting them in series will not exceed this parameter.

But the reasons to avoid this design go beyond that.

In reality, achieving the aforementioned ideal conditions is nearly impossible. The main problems are as follows:

1. Synchronization Issue

The linear motors we offer are essentially linear stepper motors, which have a defining characteristic: stepper motors operate in open-loop control. They don't know their actual position; they simply "believe" they have moved to the commanded position. If one motor encounters slightly higher friction, a sudden load change, or an inertial impact, it may "lose steps."

Critical Risk: Once one motor loses steps, even by a tiny angle, the lead screws of the two motors are no longer perfectly synchronized. They will begin to "fight" each other—one pushing while the other pulls—creating immense internal forces within the coupling and the motors themselves. This does not increase external thrust; instead, it will:

• Rapidly cause motor overheating.
• Significantly increase vibration and noise.
• Accelerate wear on mechanical components (lead screw, nut, bearings).
• In the worst case, lead to motor stall, drive alarm, or mechanical damage.

2. Mechanical Alignment Problem

Ensuring that the lead screws of two motors remain perfectly coaxial over a long distance requires extremely high precision in mechanical installation. Any slight angular misalignment or parallelism error will generate enormous lateral stress at the coupling, leading to jamming or abnormal wear.

3. Control Complexity

Even if using two independent drives and a more advanced controller to attempt true force/position synchronization (e.g., master-slave mode), the cost and complexity would far exceed simply selecting a single motor with higher thrust.

The correct approach if you need greater thrust is:

• Select a larger motor model: This is the most straightforward, reliable, and cost-effective solution. Choose a stepper motor with higher torque (larger frame size) or a linear motor model with greater thrust.
• Change motor type: If the thrust requirement far exceeds the capability of stepper motors, consider switching to other product categories.

Conclusion:

Do not attempt to increase thrust by simply connecting two linear stepper motors in series. This is a theoretically possible but practically treacherous approach. Please select a single motor with adequate thrust based on your load requirements.

Updated on: 29/12/2025