Reliance Precision Limited

Phone: +44 (0) 1484 601000     E-Mail:

Cool Muscle

The Intelligent Servo
Motion Control Package

Reliance Cool Muscle
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A Complete Motion Control Solution

This cost-effective miniature servo system combines a precision stepper motor and high resolution encoder with sophisticated drive and control electronics in a single, compact unit.

  – NEMA sizes 11, 17 and 23 each with two frame lengths

  – Encoder resolution of 50,000 counts per revolution

  – Speeds from 0 to 3,000 RPM

  – Continuous torques from 0.027 to 0.87 Nm (1.24 Nm peak)

  – H-infinity controller and vector drive for fully closed loop control of position, speed and torque.  

  – Fully programmable for standalone operation

  – RS232 and USB communications as standard

  – Options for RS485, PROFIBUS and Ethernet

  – Digital and analogue input and output

  – Safe and efficient 24V DC operation

Compared with an equivalent size of stepper motor Cool Muscle works faster, with more available torque, it is more efficient and generates less heat.

Closed loop control means no step loss. In an open loop system it is possible for the motor to fail to move the exact number of steps if it is overloaded. Cool Muscle, being a closed loop control system, is able to identify any potential for step loss and to correct it. 

Cool Muscle is available with two types of control interface: Pulse Type (P) and Computer Type (C). The P-Type is applicable for a drive and stepper system with step-pulse control, such as a PLC. Cool Muscle provides an effective drop-in solution to resolve step loss problems and also provides a more integrated solution, having a combined stepper and drive. The C-Type offers a higher level of computer control in a single integrated unit which can remove the need for a separate controller or, in more complex systems, reduce the investment required in additional controllers.

Cool Muscle’s unique features include the ability to link up to 15 motors which can operate together in complex sequences without an additional controller. Cool Muscle is able to use a physical limit of travel as its reference position, using torque sensing to safely and accurately find the limits of travel without needing a position sensor (e.g. limit switch).

The high level of integration provided by Cool Muscle reduces cabling, keeps components to a minimum and speeds up system assembly.

Cool Muscle is ideal for laboratory and test equipment or for light industrial automation.

Power-managed and energy efficient, Cool Muscle always stays cool.

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Reliance Cool Muscle Range

NEMA 11 Short

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NEMA 11 Long

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NEMA 17 Short

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NEMA 17 Long

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NEMA 23 Short


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NEMA 23 Long


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Cool Muscle Cables


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Complete Catalogue Inc Stepper Motors

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Communication Interfaces

   Options for RS485, PROFIBUS and Ethernet available, please contact our sales team for more information

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Reliance Cool Muscle Accessories

Control Room Software

Control Room is a free application which provides basic tools for setting parameters and creating motion profiles. A user friendly interface makes it easy to work with the Reliance Cool Muscle.

Control Room replaces the CoolWorks software.

CoolWorks continues to be supported by Reliance.

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RS485, PROFIBUS and Ethernet cards are available as options for the RCM servo systems. Our engineers provide technical support based on extensive experience integrating the Cool Muscle with third party controllers, HMIs, and PLCs.


Designed specifically for the RCM, this power supply is built to withstand the current draw spikes which the hard stops or starts often require. Specification of the power supply is 150 W/300 W, 6 A/10 A.


A standard motor cable (40 cm) is supplied with every motor. Longer motor cables are available as an option.

A Y-cable is required to connect the RCM to a USB or serial port.

Multi motor custom cables can be made to suit your application.

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Integrated Drives and Controls

Conventional System

Conventional motion control requires expensive drives and controls. Additional wiring for origin and limit switches increases complexity and cost.

Conventional System

Reliance Cool Muscle System

Cool Muscle eliminates the need for separate drives and motion controllers. It uses current sensing to detect limits with no need for switches and sensors.

Reliance Cool Muscle System

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Reliance Cool Muscle Types and Variations

Type C - Software Controlled


Pre Program

Based on a 32-bit RISC CPU, the integrated controller is fully programmable. Take advantage of a wealth of built-in software features to program quickly and effectively. Start programs from a PC, PLC or simple push button.

Dynamic Command

Dynamic Command

If your application requires complicated or arbitrary motion you can send commands to Cool Muscle from your PC or embedded computer.



Connect up to fifteen Cool Muscle motors together with RS232 to form an integrated, low-cost system. Use optional communications modules to add Cool Muscle to your Ethernet or PROFIBUS network.

Analogue Control

Analogue Control

Cool Muscle has built-in analogue position and velocity control, or you can take advantage of Cool Muscle’s A-to-D conversion in your own programs.

Type P - Pulse Controlled


Conventional System

Replace your existing Pulse/Direction or CW/CCW drive and stepper motor with a P-type Cool Muscle for complete freedom from step-loss. Transparently add closed-loop position and velocity control for smooth, 100% reliable positioning.

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Reliance Cool Muscle Features

Simple and Compact

No more driver/boxes. Reduced wiring. Smaller machines. Shortened development time.

An intelligent driver with a 32 bit CPU based motion controller, driver amplifier, magnetic encoder and power management are all built in right on the motor.

Simple and Compact

Full Closed Loop System

Higher repeatability, stability, and accuracy.

The Reliance Cool Muscle is a fully closed loop system. With a high resolution magnetic encoder and the intelligent driver board mounted on the back, the Reliance Cool Muscle constantly monitors every aspect of its position, eliminating any missed steps.

Closed Loop System


Using the newest control technology, the Reliance Cool Muscle goes beyond old fashioned static PID control by utilising the robust H∞ control system. H∞ responds to dynamic loads across the entire speed range, reduces the need to tune gains, and increases the allowable inertia mismatch.

Smooth and Accurate

Smooth and AccuratePerformance levels similar to AC Servos at a fraction of the price.

The Cool Muscle's high resolution encoder gives you an exceptionally fine placement of 50,000 units per rotation. The Reliance Cool Muscle uses Vector Drive Control, resulting in incredibly smooth motion, even at low speeds, not possible with microstepping drivers.

Vector Drive Control

Vector Drive is a control technique used in servo systems. Vector Drive Control is a completely different technique from micro-stepping. Unlike micro-stepping Vector Drive Control is not subject to resonance problems, produces smooth movements, increases torque and increases efficiency.

Cool Operation

Longer motor life. Increased power efficiency. Great for enclosed spaces. Reduced need for gearboxes.

The Cool Muscle's power management monitors and provides the optimum current, based on load, keeping the motor cool. In addition, using a stepping motor, the Cool Muscle generates high torque at low speeds.


Great solution for repetitive motion. Simple and compact machines.

Program the Cool Muscle to create the motion you need. Define motion profiles and create programs using easy-to-understand Cool Muscle Language (CML). Motion programs you create can be downloaded to the Cool Muscle. The programs can be executed via PC, embedded computer or simply using I/Os.


Cool Muscle Language is a set of ASCII commands which lets you create motion programs easily.

Programmable I/O

Custom I/O. Flexible application of powerfully built in features.

Configure and assign multiple functions to I/Os on the Cool Muscle. Cool Muscle has 4 inputs and 2 outputs that can be used as digital, analogue, serial or pulse counter (Input only). The new Cool Muscle lets you assign a function to each point of a signal.

Input Functions examples:

  • Origin Sensor
  • Manual Feed
  • Manual Jog
  • Execute Bank1,2,3
  • Origin Search
  • Motor Free
  • Enable Motor
  • Execute Next Step
  • Execute Previous Step

Output Functions examples:

  • Alarm
  • In-position
  • Analogue Output for monitoring


Simple network solution that lowers your cost.

The Cool Muscle provides you with different networking solutions that best suit your needs. Connect multiple Cool Muscles in a daisy chain style network. In the daisy chain network Cool Muscles can tell other motors to activate programs as well as receive commands from a computer or an embedded controller.


Advanced Motion

Change speeds or accelerations while the motor is in operation. The Cool Muscle supports advanced motions such as continuous PTP and PTP motion with different accelerations and decelerations, push mode and more. The powerful push mode is also standard allowing for electric simulation of common pneumatic operations.

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Reliance Cool Muscle - In Action

Reliance Cool Muscle Motors Offer Superior Capabilities In Laboratory Analysis Automation

Eighteen Reliance Cool Muscle motors were recently used by Labman Automation Limited, laboratory and industrial robotic solutions specialist in their new automated bottle inspection system design.

Bottles travel to one of nine test stations and are photographed and weighed to check bottle condition and filled volume. Passing these pre-requisite tests the bottles are barcode scanned and a Cool Muscle motor lowers a mechanism to check the cap tightness and to tighten the cap, if necessary. All tests passed, the bottles travel into the main bottle handling system.