US Patent 7832990 Measurement device

The invention provides a method for determining the angular position of a pump shaft relative to a pump body. The method comprises: providing the pump shaft with a first locating feature; providing the pump shaft with a second locating feature; providing a measurement device provided with a measurement member; engaging the measurement member with the first locating feature and determining a first distance between the first locating feature and a reference feature provided on the measurement device; engaging the measurement member with the second locating feature and determining a second distance between the second locating feature and a reference feature provided on the measurement device; and determining the difference between the first and second distances to provide an indication of the angular position of the pump shaft relative to the pump body. The invention also provides apparatus suitable for performing the above method.