S4 end-of-shaft slip ring 4 circuits

S4: four-circuit end-of-shaft slip ring

The S4 is an end-of-shaft slip ring with four circuits rated at 500 mA. It mounts on the free end of a rotating shaft and carries strain gages, thermocouples, RTDs, accelerometers and low voltages from rotor to stator. Precious metal rings and brushes limit the contact resistance variation to 0.1 Ω peak. The stainless steel case is sealed against dust, the bearings are lubricated for life, and color-coded solder terminals sit on both rotor and stator. With a 41.28 mm rotor, it is 30 mm long and weighs 111 g; it runs up to 12 000 rpm, from −40 to 121 °C, and a low-temperature lubricant is available below −18 °C. It is the shortest model of the series.

The rotor flange is mounted concentric and perpendicular to the shaft, on a machined shaft end or a rotor adapter, within 0.025 mm (0.001 in) of axial and radial runout. The stator is held by a flexible restraint, the S-Series restraint kit (up to 112 °C) or a worm gear clamp with a spring, never by its wires. Stranded wires, 28 or 30 AWG (24 AWG at most), run along or through the shaft and are secured to it before being soldered to the rotor terminals.

The S-Series is used, for example, to measure the torque of a gaged accessory belt pulley on an engine, or of gaged gears and gearboxes.