Hydraulics Final Exam

Direct

Heavy internal springs are used to establish the operating pressure of the ____-operating type of pressure control valves.

Series

If hydraulic motors are connected in ____, all of them operate at the same time, as long as the total pressure requirement is below the setting of the system relief valve.

Power output shaft

In the inline piston motor design, the centerline of the pistons and cylinders is inline with the centerline if the ____.

Swash plate

In the inline piston motor, a(n) ____ is used to change the linear movement of the pistons to rotary motions of the power output shaft.

20

It is typically recommended that the average fluid velocity in a hydraulic system working line should not exceed ____ per second.

One-piece; Tie rod; Threaded end; Mill

List the four basic construction types of cylinders.

Fixed centerline; Fixed non-centerline; Pivoting centerline

List the three basic configurations used to mount cylinders to equipment.

Mechanical pressure; Pilot pressure; Electromagnets

List the three sources of external force that can be used to position control valve elements.

Both pump and motor have fixed displacement; pump has fixed and motor is variable; Both pump and motor are variable displacement

List three possible pump/motor arrangements that may be used with a hydrostatic system.

Overall efficiency; Varying type and sizes of conductors; Cost; Installation drawings

Name some categories of data typically found in information sheets provided by pump manufacturers.

Provide energy to an operating system; maintain proper system operating pressures; energy displacement

Name some functions of a hydraulic system power unit.

Gear; Vane; Piston

Name the three most common, basic designs of hydraulic motors.

Operations; Construction type

Name the two common ways in which cylinders are classified.

Clevis; Trunnion

Name the two pivoting-centerline cylinder-mounting methods that allow the cylinder to follow the arc made by a pivoting machine member.

Safety valve; Hydraulic fuse

Name the two types of pressure control valves that are used to prevent damage to hydraulic systems in cases where the system relief valve fails, causing excessive system pressure.

Housing; Input/Output ports; Cap/Head

Name three basic components that make up a hydraulic cylinder.

Open and close valves; Control valve positions to determine flow

Name two basic uses of springs in the operation of hydraulic control valves.

Can act like a pump causing cavitation; Shock pressure builds up

Name two conditions that can exist when stopping a hydraulic motor, if the circuit has not been properly designed.

Flexibility; Chemical resistance; Cost

Name two factors that are important to consider when selecting hose for and installation.

Inefficient operations; High cost of maintenance; Difficult assembly

Name two situations that may result if conductors and fitting are not carefully selected for a given hydraulic system.

25

Safety valves are typically set at a pressure ____% above the setting of the primary system relief valve.

False

T or F? Low- and high-pressure hoses may be clamped together, although this is not an ideal configuration.

Center

The middle position in a three-position, four-way directional control valve is often called the ____ position. It provides a control feature beyond cylinder extension and retraction.

Laminar

The opposite of turbulent fluid flow in a pipe is called ____ flow.

Georotor

The specialized gear design that is used with most internal gear motors is called a(n) ____.

Sayborn

The system that indicates hydraulic fluid viscosity by the time it takes 60 mL of the fluid to flow through a calibrated orifice is called the ____ universal viscosity system.

Housing, rotating internal parts, and power output shaft

The three conceptual component groups that make up any hydraulic motor are ____.

Conduction, convection, radiation

The three modes of heat transfer are ____, ____, and ____.

Wipers keep out contaminants; Standard seal is used to prevent fluid leakage.

Two types of sealing components are used to seal the area around the rod of a cylinder.

Self-actuation; Mechanical; Pilot pressure; Manual actuation

What are four general categories of actuation methods used to shift directional control valves?

Shut-off; Check; Three-way; Four-way

What are the four general classifications of directional control valves used in a hydraulic system?

Bypass; Restrictor

What are the two general operating designs of flow control valves?

Springs; Pilot pressure

What are the two sources of internal force typically used to position control valve elements?

2-position

Which type of four-way valve allows cylinder extension in one position and cylinder retraction in the second position?

Springs

____ are often used on the ends of the spool in directional control valves to automatically return the valve to the normal or restart position whenever the activation force is removed.

Replenishment

____ circuits are used in closed-loop hydraulic systems to make up fluid lost from leakage during system operation.

Three-way

____ directional control valves are designed for the actuation of rams and single-acting cylinders.

Needle

____ valves are used in hydraulic systems as both shut-off and metering devices.

Ball

____ valves may be adjusted from the fully open position to the fully closed position by turning the control handle only 90 degrees (1/4 turn).

Tie rod

A cylinder that had externally mounted metal rods holding the ends on the barrel is called a(n) ____ cylinder.

Swaging

A hydraulic fitting can be attached by threads, cramping, or ____ like was demonstrated in the industrial maintenance lab.

Unbalanced

A motor in which the output shaft bearings are side located is classified as a(n) ____ design.

Externally

A pressure-reducing valve is normally open and must be ____ drained.

A cylinder

A primary component represented by a rectangle is ____.

Ram/cylinder inlet and outlet; Reservoir inlet; Pump discharge

A three-way directional control valve has the reports. Name what each port is connected to in the system.

Cylinder

A(n) ____ is the system component that converts fluid pressure and flow into linear force and movement.

Universal joint

A(n) ____ is used to connect the cylinder barrel and the power output shaft of a bent-axis hydraulic motor.

Dryseal

A(n) ____ standard pipe thread should be used when assembling pipe to prevent leakage when the joint is placed under high system pressure.

Plunger

An unloading relief valve uses a(n) ____ mechanism to assist in the operation of the balancing piston in the pilot section of the valve.

Torque

As the displacement is reduced in a variable-displacement came motor, the speed of the motor increases, while the potential ____ output decreases.

Equipment drive wheels

Can-type radial-piston motors are often used in construction equipment applications where ____ are directly mounted on the power output shaft of the motor.

Motion; Force

Control valves allow a hydraulic system to produce the type of ____ and ____ level of ____ needed for machine operation.

Speed

Controlling the flow rate of fluid entering and actuator controls the ____ of that actuator.

Restrained

Counterbalance and brake valves provide ____ control in hydraulic systems.

Operating surface area

Cylinder rod extension speed may be calculated by multiplying the flow rate going into the actuator by 232 and then dividing by the ____.

Tension

Decreasing surface ____ allows anti-foaming agents to reduce the formation of bubbles and foam in a hydraulic system reservoir.

Valve that contains a disc that ruptures when system pressure above predetermined setting is breached.

Describe a hydraulic pressure fuse.

Straight threads for O-rings; Pipe threads for attachments and fittings

Describe two general methods used for securing an adapter fitting when attaching hydraulic conductors to fittings and major system components.

Kinetic

Energy in motion is known as ____ energy.

Do work

Energy is defined as the capacity to ____.

Heat

Energy that is lost because of high flow resistance produces ____, which can cause system operating problems.

Turbulent

Excessive fluid velocity in a working line may produce ____ flow, which can result in reduced system efficiency.

Orbiting

The ____ georotor design of an internal gear motor uses a fixed gear with internal teeth and a rotating valve plate instead of crescent-shaped inlet and outlet ports.

Needle

The ____ is the simplest of the adjustable, noncompensated flow control valves.

Pilot

The ____ method of directional control activation uses system pressure, which may be remotely sensed, to shift the valve.

Valve body

The ____ serves as the holder of all working elements of the valve.

Bearing shaft

The balanced-vane motor configuration places a balanced load on the ____ of the motor.

psi

The common unit designation of pressure in fluid power systems in the U.S. is ____.

Parallel

A circuit that provides an individual route for the current to follow through each load is called a(n) ____ circuit.

Cylinder

A hydraulic ____ is an actuator that converts energy stored in the system fluid into linear motion.

1st class

A lever in which the fulcrum is located between the effort and load arms is called a(n) ____.

Combustion

A primary disadvantage of petroleum-based hydraulic fluids is low resistance to ____ which makes them unsuitable in many applications.

Manifold

A(n) ____ is a machine or fabricated element that provides a common hydraulic fluid supply to several system components.

Vent

A(n) ____ is used on reservoirs to allow the tank to take in or release air as the fluid level changes during system operation.

Reciprocating

A(n) ____ pump design uses the up-and-down linear motion of a piston in a cylinder to move fluid through the unit.

Bypass

A(n) ____ valve is used in the design of fluid power system filters to route fluid around the filter element of it becomes clogged during system operation.

Pressurized

All fluid power systems should always be treated as if they are ____ and ready to function.

Temperature, humidity

Appropriate air exchange and circulation in a work environment are important for the maintenance of suitable ____ and ____ levels.

Wedge, Screw

Examine the descriptions below and identify them with the basic machine. A: Two inclined planes fastened together ____. B: A spiral inclined plane ____.

Inlet/return valves below fluid surface levels in reservoir; Components in contact with outside environment; Internal leaks

Excessive air entrainment and foaming may be caused by a variety of hydraulic system design flaws or operational problems. Name some typical factors that can cause these problems.

Vibration

Flexible hydraulic hose is desirable in systems involving movable members or where severe ____ is a problem.

Return lines

Fluid power system filters may be located in one or more of three typical locations. List one of the three locations.

Pressurized

Fluid power systems use ____ fluid to transmit power.

Pressure

Force exerted over a unit area is known as ____.

Closed, Open

Hydraulics is a ____ system, where a Pneumatics is a ____ system.

Reservoir

Improving surface tension characteristics increases the rate at which water separates from hydraulic oils and collects in the ____.

Conductors

In a basic Hydraulic system, the ____ distribute fluid to components.

Flow control valve

In a basic hydraulic system, actuator extension speed is controlled by placing a(n) ____ I'm the line between the directional control valve and the actuator.

Impeller

In a centrifugal pump, the primary element of the pumping mechanism is called a(n) ____.

Adjustable

In a simplified symbol for a flow control valve, an arrow that passes through the orifice in the symbol indicates the valve is ____.

Three

In general, the reservoir for a stationary industrial system should have a storage capacity ____ times the flow rate of the pump.

Atmosphere

In the pneumatic fluid power system, after the pressurized system air has completed its work, it is exhausted to the ____.

Empirical Knowledge

It is generally believed by historians that much of the early development of fluid power was based on ____, rather than on an understanding of scientific principles.

Employee

It is the responsibility of the ____ to learn and follow the safety procedures needed to perform a job safely.

Viscosometer

Kinematic viscosity is measured with the aid of a device called a(n) ____.

Cost; Overall efficiency; Delivery characteristics

List factors that must be considered when selecting a pump for use in a hydraulic system.

Poor lubricant; Promotes rust; Freezes; Evaporates

List some characteristics of water that make it a poor hydraulic fluid should it be used alone in a fluid power system.

Cylinder with cap on one end with a piston inside; input line; output line; control valve

List some primary parts of a basic pump.

Roughness of surfaces, force moving the surfaces

List the two primary factors that determine the amount of friction between two surfaces.

Mechanical, muscular, electrical

List three of the five classifications of control mechanisms for which symbols are available.

Lack of hazard awareness, fear of operating a machine, impatience

List three personal factors that can cause an individual worker to perform a job unsafely.

Prevention of contamination; Decreased maintenance costs

List two reasons it is important to properly handle and maintain hydraulic fluids.

Poor lighting, poor ventilation, loud noise

Name environmental conditions from a shop setting that can cause cumulative injuries.

Condensation, vents allow some moisture when in contact with outside environment

Name two common ways that water can enter a fluid power system and contaminate the system fluid.

Copper or other catalysts in the components from manufacturing, oxygen becomes integrated through contamination, reacting with any water that may be in the fluid.

Name two conditions in a fluid power system that promote oxidation and general deterioration of a hydraulic fluid.

Extreme pressure test; Pump loading

Name two general methods that are used to establish the lubrication and wear prevention qualities of hydraulic fluids.

Power consumption, high pressure drops between components

Name two major problems that may appear if a fluid with too high of a viscosity is used in a hydraulic system.

Internal leakage, increased internal wear

Name two major problems that may appear if a fluid with too low of a viscosity is used in a hydraulic system.

Water in fluid promotes rust; Rate of maintenance increases

Name two problems that are commonly associated with the use of fire-resistant fluids in hydraulic systems.

Absolute

Standard atmospheric pressure registers as 0 psi on a gauge calibrated on the ____ pressure scale.

Neutral

Symbols are shown in the ____ position, unless they are part of a circuit diagram showing a sequence of operation.

Heating/cooling

Systems that cannot maintain appropriate fluid temperatures using ambient air temperatures and appropriate reservoir, pump, control valve, and actuator designs employ specialized ____ devices to control temperature.

Lubricator

The ____ adds a fine mist of oil to a pneumatic system to assure lubrication of system components.

Pneumatic

The ____ fluid power system can usually provide the best solution where lightweight and easily handled tools are a requirement.

Hydraulic

The ____ fluid power system is usually selected when an application requires a high operating pressure.

Reservoir

The ____ holds the system fluid not currently in use in the lines, pump, actuators and control components.

Piston

The ____ pump is the oldest of the pump designs used in current hydraulic system circuits.

Unbalanced

The ____ vane pump achieves a pumping action because the centers of the pump rotor and the cam run are off center.

Regulator

The basic pressure control device that sets maximum operating pressure in a pneumatic system is called a(n) _____.

Filtration

The cleanliness of the fluid in most hydraulic systems is assured by the addition of specialized ____ devices

Direct

The electrical current that involves electron flow in one direction only is known as ____ current.

Potential

The energy stored in a form that allows it to be easily released and used is known as ____.

Visual

The first step in testing a hydraulic fluid is to compare a sample taken from the reservoir with a sample of unused fluid of the same type and grade using a ____ inspection.

Heat

The fluid maintenance group removes dirt, moisture, and excessive ____.

Absolute

The force per unit of area required to move one molecular layer of a substance over another layer of the material is called ____ viscosity.

Film

The friction between two surfaces can easily be reduced by placing a layer of oil based liquid, called a ____, between them.

Latent

The heat required to produce a change of state in a substance, such as changing from a liquid to a solid, is known as ____ heat.

High-pressure

The hydraulic fluid additives that are used to prevent metal-to-metal contact in system components are called anti-wear or ____ agents.

Radial

The hydraulic pump that is usually considered to have the highest continuous pressure capability uses the ____-piston design.

Swash

The individual piston volumes in the inline axial-piston pump are determined by their position on an angular device called a(n) ____ plate.

Earplugs

The most popular hearing-protection devices are ____, which are both inexpensive and inconspicuous to wear.

Graphic

The most standardized graphic symbol type is the ____ symbol.

NFPA

The nonprofit trade association that concentrates its efforts in the fluid power products manufacturing area and limits its memberships to companies is the ____.

Transfer, Transmit

The physical components in a fluid power system are used to generate, ____, and ____ power to produce the desired results in an application.

Conditioning, Maintenance

The pneumatic fluid power system is generally considered to be the most expensive to operate because of the cost of ____ and ____.

Vapor

The pressure at which a fluid begins to vaporize is known as ____ pressure.

ANSI

The primary coordinating work with standardizing groups in the U.S. is done by the ____.

ISO

The principle coordinating group that works with standards on the international level is the ____.

Oitsode

The size of hydraulic system tuning is indicated by the actual ____ diameter of the tube.

110, 140

The temperature of the fluid in the reservoir of an operating fluid power system is ideally between ____ and ____ degrees Fahrenheit.

Celsius

The temperature scale that is commonly used in the world outside of the U.S. is the ____ scale.

Inertia

The tendency of a body to remain in motion once it has achieved operating speed is known as ____.

Electron, proton, neutron

The three parts of the atom are the ____, ____, and ____.

Electric motor; internal combustion engine

The two most common prime movers used in a hydraulic system are a(n) ____ and a(n) ____.

Hydraulic, Pneumatic

The type of fluid used in a system and fluid direction are indicated by a small equilateral triangle. A solid triangle represents a(n) ____ operation and an open triangle indicates a(n) ____ operation.

Watt

The unit of electrical power is the ____, which is equal to the work produced by a current flow of one ampere at a pressure of one volt.

Higher

Typically, the initial viscosity of a water-in-oil emulsion is ____ than what is recommended by system manufacturers.

Unsafe acts

Unsafe working conditions are often incorrectly identified as the chief cause of industrial accidents. What really is the chief cause of accidents?

Reduced surface tension; lowered ambient air temperatures around reservoir

What are two fundamental areas of system design and operation that must be analyzed to determine the cause of higher than desired system reservoir temperatures?

Occupational Safety and Health Administration

What does OSHA stand for?

Separates particles in the reservoir by maximizing the fluid travel path from intake to output; prevents sloshing and bubbles.

What is the purpose of baffles?

Overhead; L-shaped

What reservoir configuration is suitable for use with a pump that requires a positive pressure on the inlet line?

Hydraulic

What type of fluid power system is used when a high degree of accuracy is needed?

Boots; Cup seals

When cylinders are exposed to extreme conditions, contamination of system fluid can be reduced by using ____ or ____ to prevent the entry of dirt from the surfaces of the piston rods.

Polyglycol

Which fire-resistant fluid is similar to automotive antifreeze?

Heat

____ in the fluid of a hydraulic system is caused by forcing fluid through the system without completing work outside of the system.

Shock pressure

____ is a short duration, high pressure in a system that results from surges caused by control valves shifting or unexpected load changes during operation.

Standardization

____ is the preselected factors used as the basis for comparing items or procedures.