An improved valve for use in a hydrostatic drive apparatus for a vehicle such as a zero turn vehicle. The closure consists of a top section connected to a lower skirt portion. The actuator also optionally include a lower electrode formed on the vibrating plate. A method of using a programmable circuit to calibrate a sensor may include coupling the programmable circuit to a computer and to a testing station. Variations are comprised of a tubular plastic, such as PVC, and have the ability to be assembled in both chair and floor use configurations. In one aspect, the ring has a closed, hollow, construction, for example, a circular, oval, or polygonal closed, hollow construction.