Hydraulic Part 2

The purpose of the pressure regulator in a hydraulic system is to. maintain system operating pressure within a predetermined range and to unload the pump. regulate the amount of fluid flow to the actuating cylinders within the system. prevent failure of components or rupture of hydraulic lines under excessive pressure.

What safety device is usually located between the driving unit and hydraulic pump drive shaft?. Thermal relief valve. Pump motor safety switch. Pump drive coupling shear section.

What is one advantage of piston-type hydraulic motors over electric motors?. They are considerably quieter in operation. There is no fire hazard if the motor is stalled. They work satisfactorily over a wider temperature range.

The primary purpose of a hydraulic actuating unit is to transform. fluid motion into mechanical pressure and back again. fluid pressure into useful work. energy from one form to another.

Characteristics of MIL-H-7644 hydraulic fluid are. red color, petroleum base, will burn, synthetic rubber seals. light purple color, phosphate ester base, fire resistant, butyl rubber seals. blue color, vegetable base, will burn, natural rubber seals.

A flexible sealing element subject to motion is a. compound. packing. gasket.

What is commonly used to connect an emergency source of power, and at the same time disconnect the normal hydraulic source from critical parts of a landing gear or wheel braking system for operation (usually when the normal source system fails)?. Selector valve. Shuttle valve. Sequence valve.

The primary function of the flap overload valve is to. prevent the flaps from being lowered at airspeeds which would impose excessive structural loads. cause the flap segments located on opposite sides of the aircraft centerline to extend and retract together so that the aircraft will not become aerodynamically unbalanced to the extent that it becomes uncontrollable. boost normal system pressure to the flaps in order to overcome the air loads acting on the relatively large flap area.

A hydraulic accumulator is charged with an air preload of 1,000 psi. When a hydraulic system pressure of 3,000 psi is developed, the pressure on the air side of the accumulator will be. 1,000 psi. 3,000 psi. 4,000 psi.

The internal resistance of a fluid which tends to prevent it from flowing is called. volatility. viscosity. stability.

A flexible hydraulic hose identified as MIL-H-8788 will have a stripe running the length of the hose. This stripe is. installed without excessive twisting. for high pressure fluids with a flexing range. suitable for a wide temperature range.

How would the air pressure charge in the accumulator be determined if the engine is inoperative, but the system still has hydraulic pressure?. Read it directly from the main system pressure gauge with all actuators inoperative. Build up system pressure with the emergency pump and then read the pressure on a gauge attached to the air side of the accumulator. Operate a hydraulic unit slowly and note the pressure at which a rapid pressure drop begins as it goes toward zero.

The purpose of an orifice check valve is to. relieve pressure to a sensitive component. restrict flow in one direction and allow free flow in the other. relieve pressure in one direction and prevent flow in the other direction.

Which is a characteristic of petroleum-base hydraulic fluid?. Flammable under normal conditions. Compatible to natural rubber seals and packings. Nonflammable under all conditions.

The hydraulic component that automatically directs fluid from either the normal source or an emergency source to an actuating cylinder is called a. bypass valve. shuttle valve. crossflow valve.

Pressure is a term used to indicate the force per unit area. Pressure is usually expressed in. pounds per square inch. pounds per inch. pounds per cubic inch.

How can the proper hydraulic fluid to be used in an airplane be determined?. By referring to the Pilot Operating Handbook. By consulting the aircraft's Type Certificate Data Sheet. By consulting the aircraft manufacturer's service manual.

After installation of a rebuilt hydraulic hand pump, it is found that the handle cannot be moved in the pumping direction (pressure stroke). The most likely cause is an incorrectly installed. hand pump inport check valve. inport/outport orifice check valve. hand pump outport check valve.

Quick-disconnect couplings in hydraulic systems provide a means of. easily replacing hydraulic lines in areas where leaks are common. quickly connecting and disconnecting hydraulic lines and eliminate the possibility of contaminates entering the system. quickly connecting and disconnecting hydraulic lines without loss of fluid or entrance of air into the system.

What device in a hydraulic system with a constant-delivery pump allows circulation of the fluid when no demands are on the system?. Pressure relief valve. Shuttle valve. Pressure regulator.

What type of selector valve is one of the most commonly used in hydraulic systems to provide for simultaneous flow of fluid into and out of a connected actuating unit?. Four-port, closed-center valve. Three-port, four-way valve. Two-port, open-center valve.

Teflon hose that has developed a permanent set from being exposed to high pressure or temperature should. not be straightened or bent further. not be reinstalled once removed. be immediately replaced.

In a hydraulic system that has a reservoir pressurized with turbine-engine compressor bleed air, which unit reduces the air pressure between the engine and reservoir?. Relief valve. Air bleed relief valve. Air pressure regulator.

Hydraulic fluid filtering elements constructed of porous paper are normally. cleaned and reused. discarded at regular intervals and replaced with new filtering elements. not approved for use in certificated aircraft.

Two types of hydraulic fluids currently being used in civil aircraft are. mineral base, and phosphate ester base. mixed mineral base and phosphate ester base. petroleum base and mixed mineral base.

What is the viscosity of hydraulic fluid?. The increase in volume of a fluid due to temperature change. The fluid's ability to resist oxidation and deterioration for long periods. The internal resistance of a fluid which tends to prevent it from flowing.

Many hydraulic reservoirs contain a small quantity of fluid which is not available to the main system pump. This fluid is retained to. prime the main system. supply fluid to the auxiliary pump. supply fluid to the pressure accumulator.

The installation of a new metal hydraulic line should be made with. a straight tube to withstand the shocks and vibration to which it will be subjected. a straight tube to permit proper alignment of the fitting and thereby reduce fluid loss through leakage. enough bends to allow the tube to expand and contract with temperature changes and to absorb vibration.

A filter incorporating specially treated cellulose paper is identified as a. sediment trap. CUNO filter. Micronic filter.

If an aircraft hydraulic system requires mineral-base hydraulic fluid, but phosphate ester-base hydraulic fluid is used, what will be the effect on the system?. No effect. System will be contaminated, fluids will not blend, and the seals will fail. System will be contaminated, fluids will not blend, but there will be no seal problem.

The component in the hydraulic system that is used to direct the flow of fluid is the. check valve. orifice check valve. selector valve.

To protect seals from damage when installed over a threaded section, the threaded section should be. coated with a heavy grease. covered with tape. covered with a suitable sleeve.

Phosphate ester-base hydraulic fluid is very susceptible to contamination from. rapid changes in temperature. water in the atmosphere. icing conditions.

Severe kickback of the emergency hydraulic hand pump handle during the normal intake stroke will indicate which of the following?. The hand pump inlet check valve is sticking open. The main system relief valve is set too high. The hand pump outlet check valve is sticking open.

If the hydraulic system pressure is normal while the engine-driven pump is running, but there is no pressure after the engine has been shut off, it indicates. the system relief valve setting is too high. no air pressure in the accumulator. the pressure regulator is set too high.

(Refer to Figure 12.) Which illustration(s) show(s) the correct spiral for teflon backup rings?. 1 and 2. 3. 1 and 3.

The air that is expended and no longer needed when an actuating unit is operated in a pneumatic system is. exhausted or dumped, usually overboard. returned to the compressor. charged or pressurized for use during the next operating cycle.

Which statement about fluids is correct?. Any fluid will completely fill its container. All fluids are considered to be highly compressible. All fluids readily transmit pressure.

To check the air charge in a hydraulic accumulator,. reduce all hydraulic pressure, then observe the reading on the accumulator air gauge. observe the first reading on the hydraulic system gauge while operating a component in the system. read it directly from the auxiliary pressure gauge.

Materials which are Skydrol compatible or resistant include. epoxy paints and most common aircraft metals. polyurethane and epoxy paints. common aircraft metals, polyurethane, and epoxy paints.