hydraulic motor Flashcards
the greater the inlet flow rate supplied to a motor
the faster the drive shaft will turn
the amount of inlet pressure in a motor is determined by
the amount of resistance on a motor drive shaft
are motors able to convert all hydraulic energy into mechanical energy
no some energy is lost due to leakage and friction within the motor
as leakage and frictional losses increases in a motor
the overall efficiency of the motor decreases
why is internal leakage needed on a hydraulic motor
for lubrication and cooling of moving parts
what happens to leakage oil in a hydraulic motor
it is externally drained out through a drain line
what is the basic configuration of a external gear motor
two gears in mesh . one is connected to the drive shaft and the other is an idler .
if you were to revers the flow of oil in an eternal gear motor what would happen
the inlet port would become the outlet and the rotation of the drive shaft would change
why are external gear motors poor torque generators
because the surface area of only one tooth on each gear is providing torque and the surface area of that tooth is very small . also they are unbalanced in design not allowing high working pressures
in a gerotor and geroller motor what component rotates around the stationary internal lobe gear
the geroter star or geroller star
in order to produce one revolution of the output shaft of a orbital motor all six lobes of the motor would be exposed to oil how many times
7 ( the number of valleys in the internal gear )
what is the advantage of having internal gear lobes that roll in a geroller motor
provide better wear and less internal resistance
what is an advantage of having a disc valve in a geroller motor
the disc valve is more compact allowing the whole motor to be smaller in design
the vast majority of vane motors are
balanced because balanced vane motors can be operated at a higher pressure then unbalanced
why do vane motors use springs acting on the underside of the vanes in the rotor
to make sure the vanes have good contact to the cam ring on start up of the motor
on a balanced vane motor where are the inlet ports and outlet ports located
180 degrees apart from each other
what do the pressure plates in the vane motor provide
they keep internal clearances to a minimum minimizing internal leakage
why are balanced vane motors considered to be better torque generators then gear motors
they are more volumetrically efficient and their balanced design allows them to operate at a higher pressure than gear motors
are piston motors are the most efficient type of hydraulic motor and are also capable of generating the highest rpm
yes
what dose it mean to have a fixed displacement motor
motor rpm is directly proportional to the flow rate supplied to the motor . torque generation is directly proportional to the pressure applied to the motor
on a variable displacement piston motor changing the swash plate angle will result in
different rpm and torque characteristics of the motor
the cylinder barrel and pistons of a piston motor are often referred to as the
rotating group
what component varies the motor displacement by changing the swash plate angle on a variable displacement piston motor
the servo piston
stops on a variable axial piston motor prevent the swash plate from moving beyond a range of
6.5 to 19 degrees from perpendicular
why can a swash plate of a variable displacement piston motor never reach perpendicular
because the circuit would be hydrostatically locked and the motor would freewheel (stall)
what does it mean to have a pressure compensated motor
the motor automatically changes its displacement depending on the load applied to the output shaft
when no load is acting on the compensator spool of the pressure compensated piston motor what angle is the swash plate at
minimum angle for maximum rpm
what happens when pressure at the inlet port of a pressure compensated piston motor is great enough to overcome the compensator spring
the spool moves up in its bore allowing system pressure to act on the actuating piston . force created by the piston pushes the yoke to maximum displacement resulting in maximum displacement reducing speed and increasing torque
why is it an advantage to have the pistons fitted into sockets of the flange plate of an bent axial piston motor
because they are stronger and are not vulnerable to contamination and cavitation like axial piston motors whose shoes must slide across a stationary swash plate
what determines the displacement of the bent axial motor
the angle of the cylinder block to the drive shaft
on a variable displacement axial piston motor what alters he angle of the cylinder block in relation to the drive shaft of the motor changing the displacement
servo pistons controlled by a displacement control valve
radial piston motors are suitable for applications where
low rpm and high torque are required
on a radial crankshaft piston motor how are the pistons balanced from thrust forces acting on them
pressurized oil passes through the piston and works on the contact surface of the connecting rod and crankshaft lubricating and opposing the thrust force acting on the piston
what supplies oil to the inlet ports and allows outlet oil to return to tank on a radial crankshaft operated motor
spool valve . as the spool valve rotates with the motor output shaft ports are uncovered ensuring pressurized oil is supplied to each of the pistons and return oil is directed to the oil reservoir when the pistons are at the proper stroke
