Ground ambulances are generally much less expensive, with an average emergency run coming in at $800 to $2,000, depending on the region and other factors, according to J.D. Fuiten, secretary of the American Ambulance Association. During an emergency, when the aircraft show up, there's usually no mention of money.
The traditional electric motor on a diesel-electric or electric locomotive is a DC motor. Internally, DC motors have two main components: the stator is the stationary outside part of a motor. The armature is the inner part which rotates.
A spool valve can contain any number of individual spools each controlling its own circuit. A log splitter, for example, will have one spool operating one cylinder, the ram that splits the wood. A backhoe can have six or more functions operating off one spool valve assembly.