Wheel assembly with sensor for measuring wheel movement

A materials handling vehicle comprising:

• a power unit;
• a mast assembly secured to the power unit;
• a pair of forks coupled to the mast assembly, the forks being movable in height between a lowered position and a plurality of raised positions;
• and
• a pair of outrigger arm assemblies secured to the mast assembly,
• wherein at least one of the outrigger arm assemblies comprises a wheel assembly comprising:
• a frame member;
• an axle fixed to the frame member;
• a wheel rotatably mounted to the axle, wherein the wheel comprises a wheel recess;
• a code ring located within the wheel recess for rotation with the wheel;
• and
• a sensor device coupled to the frame member and located adjacent to the code ring, wherein the sensor device senses movement of the code ring and generates an output signal indicative of the wheel movement, and wherein:
• the frame member comprises opposing axle plates for supporting the axle, each of the opposing axle plates comprising a bore for receiving the axle;
• one of the opposing axle plates comprises a further bore extending through a thickness of the one axle plate, the sensor device being coupled to the one axle plate;
• and
• a portion of the sensor device extends at least partially through the further bore such that an outermost surface of the portion of the sensor device is flush with an inner surface of the one axle plate or recessed with respect to the inner surface of the one axle plate.