Term
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Definition
| Hydraulic Motors Convert the movement (kinetic energy) and pressure (potential energy) of a stream of hydraulic fluid into continuous moving energy of a rotating shaft. |
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Term
| What determines the torque or force output of a Hydraulic Motor. |
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Definition
| The pressure of the fluid admitted to the motor. |
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Term
| What is the general construction of hydraulic motors similar to? |
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Definition
| The general construction of hydraulic motors is similar to that of hydraulic pumps. However, some changes are made so that the mechanisms can operate as motors and be more efficient. |
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Term
| Why is efficiency important in a hydraulic motor? |
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Definition
| Efficiency is important because energy losses that occur in the system and in the hydraulic pump affect motor operation. |
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Term
| True or False - To make sure that the pump delivers as much fluid to the motor as possible, the volumetric efficiency of the pump is usually lower than its mechanical efficiency. |
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Definition
False.
The volumetric efficiency of the pump is usually higher than its mechanical efficiency. |
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Term
| How do hydraulic motors differ from hydraulic pumps in their operation? |
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Definition
| Motors need a starting or breakaway torque large enough to start rotation while fully loaded. This means overcoming the total starting friction within the motor and the connected load. Motors only have to contend with their own breakaway torques and starting friction. |
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Term
| How are hydraulic motors classified? |
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Definition
Hydraulic motors are classified by the:
1. Driving Elements
2. Principle of operation. |
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Term
| Are Hydraulic Motors Positive Displacement or Nonpositive Displacement type. |
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Definition
| Hydraulic motors are all of the positive-displacement type. |
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Term
| True or False - Hydraulic motors deliver smooth rotary movement. |
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Definition
False
Because of their construction, they have an intermittent or pulsating shaft output motion.
However, the pulsations are so small that the practical effect is one of relatively smooty motion and constant torque. |
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Term
| Name two types of positive displacement motors. |
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Definition
Fixed-displacement
Variable-displacement |
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Term
| How can the shaft output speed of a fixed-displacement motor be changed? |
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Definition
| Change the pressure ad flow rate of the hydraulic fluid that turns the motor. |
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Term
| How can the shaft output speed of a variable-displacement motor be changed? |
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Definition
| Change or alter the physical arrangement of the motor's mechanism. |
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Term
| Why are most hydraulic motors of the fixed-displacement type? |
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Definition
| Because Variable-displacement motors are more complex and less efficient than fixed-displacement motors. |
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Term
| What factors affect the rating and selection of a motor for an application? |
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Definition
1. Overall Performance
2. Operational problems
3. Speed
4. Installation Cost
5. Operating and Maintenance Cost
6. Mechanical and Volumetric Efficiency
7. Pressure range
8. Speed range
9. Starting Torque
10. Estimated Service Life
11. Size and Weight
12. Mounting Requirements
13. Noise |
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Term
| Define operating pressure of a motor |
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Definition
| The operating pressure of a motor is the pump pressure of the hydraulic system minus the line losses. |
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Term
| What determins the selection of a hydraulic motor operating speed? |
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Definition
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Term
| What governs a hydraulic motor's speed? |
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Definition
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Term
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Definition
| The torque of a motor is the twisting effect that causes a piece of equipment to rotate. |
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Term
| What is the equation for calculating the torque of a motor? |
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Definition
| Torque = 0.16* displacement(in^3)*psi*efficiency factor. |
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Term
| Name the three types of motor torque. |
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Definition
1. Starting torque.
2. Running torque
3. Stalling torque |
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Term
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Definition
| The starting torque is the turning force the motor exerts from a dead stop. |
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Term
| What What is running torque? |
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Definition
| Running torque is exerted when the motor is running and changes whenever there is a change in fluid pressure. |
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Term
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Definition
| Stalling Torque is the force necessary to stop the motor. |
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Term
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Definition
| An Ideal Motor is defined as having no power losses due to friction and leakage and is 100% efficient. |
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Term
| What is the formula to calculate the mechanical horsepower output of a hydraulic motor? |
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Definition
| HP=torque(lb-in)*shaft speed(rpm)/63,025 |
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Term
| What is the formula for calculating input horsepower? |
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Definition
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Term
| What is the formula for calculating overall efficiency? |
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Definition
| overall efficiency = output hp/input hp |
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Term
| What is the formula for calculating flow? |
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Definition
| flow(gpm) = (displacement(in^3)*shaft speed(rpm))/231 in^3/gal |
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Term
| When selecting a replacement motor for an existing system what fluid characteristics must be considered. |
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Definition
1. Viscosity
2. Viscosity Index
3. Volatility
4. Resistance to foaming
5. Oxidation and corossion resistance
6. Fluid effects on seals. |
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Term
| What is the typical service life for hydraulic motors? |
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Definition
Similar to that of pumps
1000 hrs to 15000 hrs depending. |
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Term
| What are the different types of hydraulic motor construction? |
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Definition
1. Gear
2. Vane
3. Axial-piston
4. Rotary-piston |
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Term
| What are the three types of hydraulic gear motors? |
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Definition
1. External
2. Internal
3. Nonseperated |
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Term
| How is the displacement adjusted in a variable-displacement axial-piston motor? |
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Definition
| By manually or automatically changing the angle of the swash plate. |
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Term
| Internal gear motors--inner & outer gear set with an output shaft. The inner geear has 1 less tooth than the outer gear. |
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Definition
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Term
| 2 matching gears in an enclosed housing. One output shaft & 1 idler shaft. |
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Definition
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Term
| Matched gears; similar to an internal gear motor. |
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Definition
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Term
| Balanced--shaft is balanced to prevent shaft & bearing wear. Designed to have 2 inlets & 2 outlets internally. |
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Definition
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Term
| Unbalanced--load can stress the shaft & bearings |
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Definition
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Term
This motor can be fixed or variable displacement, several styles;
in-line axial
Bent axis axial
Radial |
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Definition
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