Railroad Speed Sensors Applications

MAGNETIC SENSORS CORPORATION (MSC) continues to be an innovator on speed solutions for railway applications. MSC's Variable Reluctance (VR) engine cam and crank shaft speed sensors are used extensively in diesel electric locomotives. MSC's engine cam and crank sensors have very high reliability.  An MTBF of millions of hours has been demonstrated.

Hall Effect sensors usually sense a rotating target wheel or gear. The sensor, with its head at a precise distance from the target wheel, detects the magnets or teeth passing its face.  The sensor provides up to four independent channels of output that can be sampled by train control systems and braking controllers. In addition to sensing speed, the sensors are also used to calculate distance traveled by multiplying the number of rotations of the wheel by wheel circumference.

Traction Motor speed sensors are used extensively in rail vehicles for the critical speed control and braking systems. Locomotives depend on a reliable and precise rotary speed signal, to measure speed or changes in speed, particularly on traction and train. Although drives without sensors are also used, most locomotives with traction motor need a rotary speed sensor for their regular system. The speed sensors are mounted to traction motor which feedback speed to the traction motor and the drive train Engine Control Module.


PT1000 temperature sensors are used in environments with a need for high accuracy over a wide temperature range. This temperature sensor uses a 2 wire, Class B, PT1000 element with a measuring range of -50ºC to +400ºC and has an operating temperature of -25ºC to +85ºC. The temperature sensing element is housed in a stainless steel enclosure and is 100% encapsulated in a high-temperature, thermally conductive epoxy to ensure highly reliable performance in the severe environment encountered in train bogies (i.e., trucks). 

The probes have an ingress protection rating of IP69K (pressurized steam). The sensor has a 90º elbow coupled to the cable so that the cable can exit the temperature probe without being subjected to excessive bending stresses. The cable is then protected throughout its length by a flexible conduit. In addition to the positive and negative conductors, a third conductor (ground) is included in the cable so that the temperature probe ground potential can be determined at the site of the signal conditioner through a 6 pin Harting connector.