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Figure 10-11.Applications of actuating cylinders.
Vane-Type Motor  

Fluid Power - Intro to Hydraulics, Pneumatics, and how it all works
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MOTORS controlled  by  either  a  four-way  directional  control valve  or  a  variable-displacement  pump. A fluid power motor is a device that converts fluid  power  energy  to  rotary  motion  and  force. The  function  of  a  motor  is  opposite  that  of  a pump.   However,   the   design   and   operation   of fluid  power  motors  are  very  similar  to  pumps. Therefore,  a  thorough  knowledge  of  the  pumps described in chapter 4 will help you understand the  operation  of  fluid  power  motors. Motors  have  many  uses  in  fluid  power systems.  In  hydraulic  power  drives,  pumps  and motors are combined with suitable lines and valves to  form  hydraulic  transmissions.  The  pump, commonly referred to as the A-end, is driven by some  outside  source,  such  as  an  electric  motor. The pump delivers fluid to the motor. The motor, referred to as the B-end, is actuated by this flow, and  through  mechanical  linkage  conveys  rotary motion and force to the work. This type of power drive is used to operate (train and elevate) many of   the   Navy’s   guns   and   rocket   launchers. Hydraulic motors are commonly used to operate the wing flaps, radomes, and radar equipment in aircraft. Air motors are used to drive pneumatic tools.  Air  motors  are  also  used  in  missiles  to convert the kinetic energy of compressed gas into electrical  power,  or  to  drive  the  pump  of  a hydraulic  system. Fluid motors may be either fixed or variable displacement.   Fixed-displacement   motors   provide constant torque and variable speed. The speed is varied  by  controlling  the  amount  of  input  flow. Variable-displacement motors are constructed so that  the  working  relationship  of  the  internal  parts can   be   varied   to   change   displacement.   The majority  of  the  motors  used  in  fluid  power systems are the fixed-displacement type. Although  most  fluid  power  motors  are  capable of  providing  rotary  motion  in  either  direction, some  applications  require  rotation  in  only  one direction.  In  these  applications,  one  port  of  the motor  is  connnected  to  the  system  pressure  line  and the other port to the return line or exhausted to the  atmosphere.  The  flow  of  fluid  to  the  motor is  controlled  by  a  flow  control  valve,  a  two-way directional  control  valve,  or  by  starting  and stopping  the  power  supply.  The  speed  of  the motor  may  be  controlled  by  varying  the  rate  of fluid  flow  to  it. In  most  fluid  power  systems,  the  motor  is required  to  provide  actuation  power  in  either direction.  In  these  applications  the  ports  are referred to as working ports, alternating as inlet and outlet ports. The flow to the motor is usually Fluid motors are usually classified according to the type of internal element, which is directly actuated by the flow. The most common types of elements are the gear, the vane, and the piston, AU three of these types are adaptable for hydraulic systems,  while  only  the  vane  type  is  used  in pneumatic  systems. GEAR-TYPE   MOTORS The   spur,   helical,   and   herringbone   design gears  are  used  in  gear-type  motors.  The  motors use  external-type  gears,  as  discussed  in  chapter  4. The operation of a gear-type motor is shown in  figure  10-12.  Both  gears  are  driven  gears; however,  only  one  is  connected  to  the  output shaft. As fluid under pressure enters chamber A, it  takes  the  path  of  least  resistance  and  flows around the inside surface of the housing, forcing the   gears   to   rotate   as   indicated.   The   flow continues through the outlet port to the return. This  rotary  motion  of  the  gears  is  transmitted through  the  attached  shaft  to  the  work  unit. The motor shown in figure 10-12 is operating in one direction; however, the gear-type motor is capable   of   providing   rotary   motion   in   either direction. To reverse the direction of rotation, the ports  may  be  alternated  as  inlet  and  outlet.  When fluid is directed through the outlet port (fig. 10-12) into chamber B, the gears rotate in the opposite direction. Figure  10-12.—Gear-type  motor. 10-8







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