CAD 154 - HYDRAULIC CANVAS QUESTIONS

An actuator cannot move a load until?

Fluid pressure increases enough to support the load.

What hydraulic component applies a force to a fluid and causes it to flow?

Pump

The volume of fluid that flows within a given amount of time is measured as fluid _______?

Flow rate

To increase fluid velocity within a hydraulic system, you can?

Increase flow rate from the pump or use conductors with a smaller cross sectional area.

If confined and exposed to an applied force, fluid ______.

Exerts pressure equally in all directions.

If unconfined and exposed to an applied force, fluids _____.

Flows

The amount of time it takes for a given amount of fluid to move a certain distance is measured as fluid ________?

Velocity

What happens to fluid flow rate and pressure if fluid flow is resisted?

Flow rate decreases and pressure increases.

What two factors affect the maximum pressure that can develop within a system?

Input force and the area on which the input force is applied

What occurs in a hydraulic system when fluid pressure increases to the level required to support a load?

Fluid flows to move the load

What occurs in a hydraulic system if fluid flow is resisted?

Fluid flow rate decreases and fluid pressure increases

How can fluid flow rate through a hydraulic system be reduced?

Restrict fluid flow from the pump

Under what conditions will the amount of output force produced by hydraulic system be greater than the amount of input force applied to the system?

Area on which fluid exerts pressure to produce the output force is greater than the area on which the input force is applied

Which hydraulic component is designed to use fluid flow and pressure to produce mechanical motion and thus do work?

Actuator

What two factors affect the maximum amount of load that the hydraulic system can support?

Maximum fluid pressure and the area on which that pressure is exerted

What two factors affect the amount of fluid pressure required to lift a load?

Resisting force of load and the area on which fluid exerts pressure to support the load

In which type of piston pump does fluid enter the pump as pistons riding along an angled rotating plate move out of the bores in a stationary cylinder barrel?

Wobble plate

Which type of actuator contains an assist cylinder that enables a working cylinder to extend the piston rod one-half of its total stroke length?

Duplex

During the first half of rotation of a vane pump fluid enters the pump as vanes move:

Out of rotor slots, increasing the size of pumping chambers

In variable-displacement vane and radial piston pumps, displacement is changed by varying the:

Offset between the center of a ring and the center of the rotating element

In axial piston motors, the greater the angle between the cylinder barrel and the plate, the:

Greater the produced torque and the slower the drive speed

Which type of cylinder uses fluid pressure to move the piston in one direction and spring pressure to move it in the opposite direction?

Single acting

In which type of pump does an inner gear with external teeth rotate within an outer gear that as internal teeth?

Gerotor

Which cylinder component is designed to support the piston rod as it moves in and out of the cylinder?

Rod gland bushing

In which type of hydraulic pump is fluid carried from inlet port to outlet port in sealed chambers?

Positive displacement

In which type of piston pump is fluid delivered as pumping chambers decrease in size as pistons riding along a reaction ring move into bores within a cylinder block?

Radial piston

Which cylinder component prevents the piston from slamming against the end caps at the end of each stroke?

Cushion

In the unbalanced design of a vane pump, fluid flowing on only one side of the pumping mechanism can result in _____.

Excessive stress on the drive shaft and bearings

A pump containing a compensation mechanism causes pump displacement to decrease when fluid ____.

Pressure increases

In a double-acting differential cylinder, the forward stroke is _____.

Slower but develops more force than the return stroke

In an external gear pump, pumping chambers are formed between the ____.

Gear teeth and the pump housing

In a rotary actuator, limited-arc motion is produced as fluid entering a chamber exerts pressure to move a _____.

Vane

A pump’s delivery rate can be changed by varying either the ____.

Pump’s displacement or the speed of the drive shaft

In which type of hydraulic pump do sealed chambers increase in size to draw fluid into the pump and decrease in size to force fluid out of the pump?

Positive displacement

In which type of cylinder is output force doubled as fluid pressure is exerted against two pistons, that are connected by a common piston rod?

Tandem

In which type of piston pump does fluid enter pumping chambers as pistons, riding along a stationary angled plate, move out of bores in a rotating cylinder barrel?

Swash plate

Fluid is drawn into a positive displacement pump as a slight vacuum forms _____.

At the pump inlet

In which type of pump does fluid enter the pump when pumping chambers increase is size as pistons riding along a reaction ring move out of bores in a cylinder block?

Radial piston

 In axial-piston pumps, displacement is varied by changing the ____.

Size of angle between the cylinder barrel and the plate

In which type of hydraulic pump does delivery dramatically decrease as fluid pressure increases?

Centrifugal

In vane pumps, reverse flow through the pump can be achieved by _____.

Moving the cam ring to an under-the-center position

Which type of pressure control valve should be used to prevent a cylinder from dropping a heavy load?

Counterbalance

Sequence valves should be _____.

Normally closed, internally controlled, and externally drained

In which type of valve does spring pressure hold a spool in a position to block the flow path through the valve?

Normally closed pressure control

If reverse flow through a pressure control valve is required, the valve should contain a(n) _____.

Check valve

When a float-center spool is centered within a four-way directional control valve, _____.

The pump port is blocked and both actuator ports are open to the return port

Which type of actuation mechanism for a directional control valve uses an electrical device to produce the linear motion required to position the valve spool?

Solenoid

The pressure differential across the restriction of a pressure-compensated flow control valve is equal to the pressure exerted by _____.

The valve spring

Which type of pressure control valve should be used to divert flow form the pump to the reservoir between actuator cycles?

Unloading

In a pressure-compensated flow control valve, if the pressure differential across the valve increases, flow rate through the valve _____.

Is not affected

Compound or pilot-operated valves are designed to _____.

Prevent the main valve from responding to short-duration pressure surges

The flow path through a normally closed pressure control valve is open when ____.

Fluid exerts enough pressure to counteract valve spring pressure

In normally open pilot-operated pressure control valves, fluid flowing through the pilot valve passes through the _____.

External drain and returns to the reservoir

Which type of valve is designed to respond to pressure changes beyond the valve?

Normally open directly operated pressure control valve

Unloading valves should be _____

Normally closed, externally controlled, and internally drained

Sequence valves should be _____.

Normally closed, internally controlled, and externally drained

Pressure reducing valves should be _____.

Normally open, internally controlled, and externally drained

Which type of pressure control valve is designed to prevent flow to one actuator or section of the system until pressure reaches a preset level?

Counterbalance

Which type of pressure control valve should you install in a system to prevent a hydraulic motor from “running away?”

Brake

Which type of valve restricts fluid flow in one direction and permits fluid to flow freely in the opposite direction?

Flow control valve with reverse-flow check valve

In a simple flow control valve, if the pressure differential across the valve increases, the flow rate through the valve _____.

Increases

Pressure-compensated flow control valves are designed to _____.

Maintain a constant flow rate through the valve

Which type of directional control valve always permits free flow in one direction but can either block or permit flow in the opposite direction?

Pilot-operated check valve

Which type of directional control valve regulates fluid flow to and from a double-acting cylinder?

Four-way

When a tandem-center spool is centered within a four-way directional control valve, _____.

the actuator ports are blocked and the pump port is open to the return port

Which type of actuation device for a directional control valve uses fluid directed by a pilot valve to control spool position?

Pressure actuation

O-rings, T-rings, and cup seals are used to seal

Cylinder pistons

What output pressure does an intensifier develop if the input pressure is 500 pounds per square inch (psi), the area of the piston is 4 sq. in. and the area of the ram is ½ sq. in.?

4,000 psi

Which hydraulic component is designed to store fluid at high pressure?

Accumulator

Within what velocity range should fluid flow through a pump suction (intake) line?

2 to 4 ft/sec

Dry-seal threads are used on pipe fittings to _____.

Ensure an interference fit

Hydraulic hosing consists of ____.

Alternating layers of synthetic rubber and braided fabric or wire mesh

Which type of filtering element removes contaminants from hydraulic fluid by forcing the fluid to pass through several layers of material containing varying sized pores?

Depth

Which part of a reservoir prevents fluid returning to the tank from being immediately drawn into the pump intake line?

Baffle

If a hydraulic hose has a burst pressure of 4,000 pounds per square inch (psi), it should not be used in systems in which the working pressure is greater than ____.

1,000 psi

If a fluid’s thickness changes a great deal in response to temperature changes, the fluid has a ____.

Low viscosity index

Which component is designed to absorb shock and counteract small pressure fluctuations within a hydraulic system?

Accumulator

To avoid changes in fluid thickness as fluid temperature changes, hydraulic fluid should have a _____.

High viscosity index

Types of seals used to seal cylinder piston rods (rod gland seals) include ____.

Compression packings and lip seals

In which type of fitting does a tapered cylinder provide an interference fit between a compression nut and the connector?

Ferrule

Dry-seal threads seal more effectively than standard pipe threads because _____.

The crests of dry-seal threads before their flanks contact

What can occur if fluid level within the reservoir is too low?

Air will be drawn into the intake line

Which component is designed to store fluid, dissipate heat, and allow contaminants to settle and entrained air to escape?

Reservoir

The main functions of hydraulic fluid include transferring power, _____.

Lubricating bearings the internal surfaces of components, and sealing closely mating parts

When the pressure exerted by hydraulic fluid at a gas-loaded accumulator is greater than the pressure exerted by the accumulator’s nitrogen gas, the ____.

Fluid enters and charges the accumulator

If a hydraulic system has a working pressure of 4,000 pounds per square inch (psi), conductors should have a burst pressure rating of at least _____.

16,000 psi

If a system contains an intensifier with a 5-sq in. piston and a 2-sq. in. ram, what output pressure develops if an input pressure of 400 pounds per square inch (psi) is exerted against the piston?

1,000 psi

Which type of filtering element removes contaminants as fluid flows through small pores of a single layer of cloth or perforated material?

Surface

What is the effect on system operation if cross-sectional area of a hydraulic conductor is too small?

High fluid velocities and high fluid pressures

When a filtering element becomes clogged, what change in system operation causes a filter indicator to show this condition?

Increase in fluid pressure preceding the filter

Which type of hydraulic component is designed to maintain proper fluid temperature?

Heat exchanger

Which hydraulic component permits fluid to flow in one direction and blocks it in the opposite direction?

Check valve

Which hydraulic component uses linear motion to transfer the mechanical energy received from the prime mover into fluid energy?

Reciprocating pump

Which hydraulic component is represented by the following graphic symbol?

Engine

Which component supplies mechanical input energy to a hydraulic system?

Prime mover

Which actuator would you select if a load must be moved linearly in one direction only?

Single-acting cylinder

In which hydraulic valve is fluid blocked in both directions through the valve until actuation of the valve opens a flow path?

Normally closed two-way valve

Which hydraulic component is represented by the following graphic symbol?

Pump

Which hydraulic component is designed to control the direction of fluid flow to and from a single- acting cylinder?

Three-way valve

Which hydraulic component is represented by the following graphic symbol?  

Check valve