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Linear Servomotors

Nippon Pulse's Linear Shaft Motor is a brushless, high-precision, direct drive linear servo motor with a tubular design. The motor is a direct drive linear servomotor, which consists of a magnetic shaft and coil assembly (forcer) and is driven and controlled by the flow of current. They can replace ball-screws, pneumatics, U-shaped motors and other linear motion systems.

Design concepts

  • Simple: Two parts and a non-critical air gap
  • Non-contact: No wearing and maintenance free
  • High precision: Ironless design uses all the magnetic flux

Specification overview

  • Range of shaft diameters: 4mm to 100mm
  • Stroke lengths: 20mm to 4.6M
  • Achievable peak force: 2340N
  • Maximum continuous force: 585N

Advantages of Linear Servomotors

Applications of Linear Servomotors

Choosing the best Linear Servomotors for your application

3D Models

More information

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Traditional motion systems

The linear shaft motor is the first linear servomotor designed for the ultra-high-precision market and, as a result, has several advantages over traditional linear systems. The linear shaft motor is compact and lightweight, has no cogging issues, is up to 50 percent more energy-efficient than traditional linear motors, and features a non-critical air gap, which reduces maching costs.

Lead screw

The advantages of the linear shaft motor include higher velocities [>240 in/sec (>6 m/s)], non-wear moving part, free movement when power is off, no backlash because there are no mechanical linkages, easier alignments, and easier manufacturing.

Benefits of Linear Servomotors


The servo motor consists of only two parts: a magnetic shaft and a "forcer" of wound coils. More than one forcer can be used in conjunction with a single shaft as long as the forcers do not physically interfere with each other. Two forcers may be tied together and driven with one drive to double the output force.

Because of its simple structure, the linear shaft motor experiences minimal wear and is entirely maintenance-free.

However, Nippon Pulse recommends you perform periodic inspections on all systems, including the bearings and supports. See the maintenance and service section of the Installation and users' guide for details about the recommended inspections.


The linear shaft motor offers ultra-high precision because it has no iron in the forcer or shaft. This allows for the precision and zero cogging expected in a coreless design while providing the stiffness expected in an iron-core motor.

Because the forcer coil completely wraps around the shaft's internal magnets, all the motor's magnetic flux is efficiently used. This allows for a 0.5mm to 2.5mm nominal annular air gap between the shaft and forcer. This air gap is non-critical, meaning there is no variation in force as the gap changes over the stroke length of the device.


The linear shaft motor is a high-performance, accurate motor. Standard rotary motor electronics work with linear motors, and there is no need to convert rotary motion to linear motion, which is a major source of positioning error among rotary-to-linear systems. While the linear shaft motor does not have inherent resolution, position accuracy is ultimately determined by the linear encoder feedback accuracy and the core stiffness of the motor.

Testing has shown that with encoder resolutions less then 10nm, the linear shaft motor will, at worst, enable a position accuracy of ±1.2 pulses of encoder resolution. This position accuracy is not affected by the expansion and contraction of the shaft.


The linear shaft motor can be built for a variety of operating environments, including in water, vacuums, or clean rooms.


Linear shaft motors use rare-earth magnets, which are the strongest magnets available, producing magnetic fields that are significantly stronger than any other type of magnets. However, when operating at high ambient temperatures (>80°C), these magnets can lose strength. Lower temperatures have no effect on the magnets.


A linear shaft motor's maximum speed is a two-step calculation. First, max acceleration is calculated by (acceleration = accl force / mass). Second, the maximum speed is calculated by (velocity = acceleration * time). Outside of this, the linear shaft motor itself does not have inherent speed limitations, although there are factors that can limit the maximum speed.

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