There are several ways to measure the position of a rotary axis, and some position measuring devices, such as incremental and absolute encoders, can also derive the speed of the axis by evaluating a combination of distance, time, and pulses. But for applications that require only speed measurement — without position information — a tachogenerator may […]

Runout is a dimensional specification that defines error in the motion of a surface as it moves relative to a datum. The official geometric dimensioning and tolerancing (GD&T) definition of runout applies to the variation of a circular feature — such as a shaft or spindle — as it rotates over 360 degrees, although the term […]

The first place to start when sizing a gearmotor is to determine the required output torque and speed. But once torque and speed are defined, you’ll also want to know the required input power for the motor — particularly if the gearmotor uses an AC induction motor, where the power rating (typically given in horsepower) […]

When sensors, actuators, and other lower-level components are used in a functional safety capacity, AS-Interface Safety at Work offers a simple, efficient, bus network for monitoring these safety devices — alongside standard, non-safety devices — on the AS-Interface cable. Recall that actuator-sensor interface (AS-Interface, or simply AS-I) is a master-slave bus that operates at the […]

Was there once life on Mars? This is the question that one of the most complex robotic systems ever built by humankind has set out to answer. Several of maxon’s electric drives are used for handling the soil samples — and to control the first Mars helicopter. The rover named Perseverance entered the atmosphere of […]

A crossed roller bearing is a type of rotary bearing that uses cylindrical rollers arranged in a crisscross pattern, with each roller oriented at a 90 degree angle relative to the one adjacent to it. This arrangement allows crossed roller bearings to withstand radial, axial, and moment loads, so they can often replace dual-bearing arrangements, for […]

Rotary actuators — and their counterparts, rotary stages and rotary indexing tables — are designed to move loads radially with high positioning accuracy. Similar to linear actuators, sizing a rotary actuator requires evaluating parameters such as torque, speed, and inertia, as well as ensuring the actuator can meet the application requirements for positioning the load, such […]

Although servo systems can very precisely control motor speed, position, and torque, in some applications, the motor may not be able to reach the commanded velocity due to limits in the available bus (supply) voltage from the drive. But advanced servo drives offer a technique referred to as field weakening, which alters the motor’s torque-speed […]

Friction, which is the resistance to relative motion between two bodies, occurs in all sliding and rolling motions. In components that use lubrication to separate rolling or sliding surfaces — such as bearings and gears — there are typically two types of friction: static friction and dynamic friction. Static friction — also referred to as “stiction” […]

In servo-driven systems, feedback for position, velocity, and/or torque control is typically provided by a rotary encoder or resolver mounted to the motor. But mechanical components and connections in the drivetrain — such as gearboxes, ball screws, and couplings — are not perfectly rigid and introduce backlash, compliance, and windup into the system. This lack […]

When we think about actuators, we typically think about linear actuators — devices that move loads in a straight line, driven by a screw, belt, or other mechanical power transmission device. But there also exists a class of actuators that provide rotary motion for positioning a load radially around a fixed axis. While these rotary […]

Any time current flows through a wire — such as the windings in a motor — resistance in the wire, as well as other losses, cause heat to be generated. This heat will eventually transfer to other parts of the motor, causing them to degrade over time. One of the key components affected by this […]

When an electrical device, such as an AC induction motor, is switched on, it experiences a very high, momentary surge of current, referred to as inrush current. When an AC induction motor is started, the supplied voltage creates a magnetic field in the stator, which induces a magnetic field in the rotor. The interaction of […]

Manufacturing plants often contain dozen, if not hundreds, of motors — driving everything from packaging and processing equipment to fans and pumps. Motor control centers allow facilities such as these to centralize control of some or all of their motors into one location. The basic structure of a motor control center (MCC) is a metal cabinet […]

The term “motion control” spans a wide range of applications that involve controlling the movement of a linear or rotary axis to achieve a goal such as moving to a specified position or precisely following a defined path. And although there are numerous variations, at their core, many of these applications can be grouped into […]

Shear pin torque limiters are a simple, cost-effective design for protecting equipment from torque overloads. In their most basic form, they incorporate a pin (or, for very high torque ratings, multiple pins) inserted between two rotating elements, such as discs or flanges. When torque is being transmitted from the driving to the driven load, the […]

Rotating equipment such as motors, gearboxes, and fans can experience a torque overload if the system encounters an unexpected malfunction such as a jam or crash of the driven load. One way to protect these expensive components — and to avoid physical injury to personnel — is to install a torque limiter in the drive […]

Relays are used in motor-driven applications to measure and monitor operating parameters such as temperature, current, or voltage, preventing damage to the motor and connected equipment in the case of a fault or abnormal operating condition. Voltage monitoring relays can detect not only under-voltages and over-voltages, but also voltage-related issues such as phase imbalances, phase […]

A common function of a conveyer system is to accumulate products — in other words, to stop them from moving along the conveyor to create a buffer, establish a queue, or smooth out differences in material movement between upstream and downstream operations. But traditional accumulation methods allow products to bump into each other and stack up […]

Electromechanical switches are often placed at the ends of linear axes to indicate the limits of travel. But for applications with rotary — rather than linear — motion, geared cam limit switches can perform a similar function by tracking rotations of the motor shaft and triggering switches to stop movement when the specified number of […]

Heat is a major factor in the performance and life of a motor, and one of the primary sources of motor heating is current running through the motor windings. Since heating is an unavoidable condition of motor operation, it’s important to protect the motor from overheating, or thermal overload. In a previous post, we described […]

When a motor’s rotor speed is greater than its synchronous, or designated, speed, it can act as a generator, creating electrical energy from mechanical energy. This electrical energy needs somewhere to go, and there are two ways to deal with it — dissipate it as heat, or reuse it. Dynamic braking takes the energy generated […]

Busbars are components that facilitate the distribution of power to electrical equipment, supplementing or replacing traditional wiring in applications such as commercial facilities, data centers, and industrial plants. At their most basic, busbars are relatively simple bars, strips, or rods made of copper, brass, or aluminum, but in many cases, they’re constructed in specific shapes […]

Pulse-width modulation is a fundamental operating principle of variable frequency drives (VFDs), but the high-frequency switching that delivers pulses of voltage from the drive to the motor can cause bearing currents — high-frequency currents that flow through the motor bearings, often leading to damage and premature failure. To achieve pulse-width modulation, insulated gate bipolar transistors (IGBTs) […]

Variable frequency drives use a technique referred to as pulse-width modulation (PWM) to provide voltage of varying frequency to an AC induction motor. The inverter, or output, stage of the VFD uses insulated gate bipolar transistors (IGBTs) that switch on-and-off rapidly, creating trapezoidal pulses of varying width to simulate AC sinusoidal voltage. But the windings in […]