Hydraulic Trouble shooting, math, fluid seals test Flashcards
when troubleshooting a hydraulic system on site you would
use a schematic of the system
ask a journeyman for help
talk with the operator
all the above
All of the above
when troubleshooting a hydraulic system on site you would
use a schematic of the system
ask a journeyman for help
talk with the operator
all the above
all of the above
if a hydraulic pump has lost some of its efficiency you would know this by
slow moving actuators
loss of pressure
excessive oil flowing thru the pump’s drain line when tested
both the first and 3rd answers
Both the first and third answers are correct
Areation is caused by?
-entrained air bubbles in the oil
- Leaking pump seals
- to much oil in the tank
- all of the above
leaking pump seals
Cavitation which is distinguished by a rattling noise is checked by?
- Looking for a clogged inlet
- Installing a vaccum gauge on the pressure line
- installing a flow meter on the drain line
- All of the above
looking for a clogged inlet
Misaligned couplings lead to?
- loose mounting bolts
- broken drive shafts
- vibration
- all of the above
all of the above
an axial piston pump with a variable displacement could have ______ if the flow or pressure was low?
- The pressure or load sensor out of adjustment
- A blockage in the pilot port to load sensor or compensator
- all of the above
all of the above
low output speed of an actuator could be caused by?
- A volume control valve
- A pressure reducing valve
-A directional control valve
-All of the above
A volume control valve
an AC solenoid can burn out and can be noisy (hum)
true
false
true
To test a directional control valve for proper actuation, you could
push the armature pin or manual override to see if the actuator moves
see if the hoses jump when the valve is energized
see if the light comes on at the end of the directional control valve when it is energized
all the above
all of the above
a compound (pilot operated) relief valve has ___________then a direct acting
a higher override
less stages
lower pressure override
all the above
lower pressure override
a most likely problem with a relief valve is a broken spring
true
false
True
a pressure reducing valve is a normally closed valve. (senses pressure up stream of the valve
true
false
False
down stream of the valve
a sequence valve has an external drain line to the tank
true
false
True
a counterbalance valve that will not let the load lower has what type of problem
broken spring
worn valve
incorrect adjustment (set to low)
incorrect adjustment (set to high)
Incorrect adjustment (set to high)
after installing a flow control, the speed of the actuator is slow in the wrong direction. the problem is
dirt on the valve seat
incorrect adjustment
worn throttle spool
valve installed backwards
Valve is installed backwards
to test a cylinder for leaks, pressurize either end and see if any oil comes out the other end.
true
false
True
if oil comes out it means oils is flowing past the piston
if a cylinder has jerky movement or is squealing, the most likely cause would be aeration
true
false
True
hydraulic motors that are not producing full torque (pressure) have what kind of problem
internal leakage
shaft seal leaks
relief valve set to low
all the above
Relief valve set to low
other answers are flow issues not pressure
when troubleshooting hydraulic systems, the things to look for to solve the issues are
pressure
speed
heat
all the above
all of the above
to help troubleshoot a system you need to know how the system works
true
false
True
a tachometer will help you troubleshoot what type of issues
flow
speed
pressure
both the 1st and 2nd answer
flow and speed
pressure gauges are protected from damage (from pressure spikes) by the use of snubbers
true
false
True
if you were checking if there was any flow going over the relief valve, you would use a
flow meter on the outlet side of the relief valve
temperature gauge on the pump
flow control at the actuator inlet
none of the above
Flow meter on the outlet side of the valve
particle counters count particles at 3 different micron ratings. they are
2, 5, 10
2, 10, 20
4, 6, 14 or 2, 5, 15
2, 4, 14
4,6,14 or 2,5,15
when troubleshooting electro-hydraulics with a servo valve, you would know it would
be an open loop system
be a closed loop system
be controlled by air
not have feedback
Be a closed loop system
servo valves have amplifier cards that convert an electronic signal from the feedback device to the servo valve____________________
torque motor
encoder
transducer
tachometer
Torque motor
when troubleshooting a system with many branches or circuits within the system, you would use a schematic with a solenoid chart to help resolve the issue(s)
true
false
True
a common fault with servo valve systems that make them inoperable is a plugged filter.
true
false
True
a starting point to solve hydraulic issues when a system is not working properly is to talk to the operator running the system
true
false
True
what is the force(lbs) if 500 psi is applied to the low pressure side of an intensifier cylinder? the area on the input side is 10 sq in and the output piston is 1 sq in
500
100
2500
5000
5000
what is the load the porta-power system will lift. m.a. of handle=15/1, piston d=0.5”, ram D=3”, E=50 lbs
27,000 lbs
12,000 lbs
17500 lbs
22500 lbs
27000 lbs
calculate the HP required to drive a pump in a hydraulic cylinder hydraulic system with the following specifications. ram piston diameter=3”, piston rod diameter=1.5”, return stroke force= 6000lbs, return stroke speed= 350 in/min
7.4
6.2
4.8
5.3
5.3
a hydraulic hoist must not lift any vehicles over 5000 lb. the piston diameter=10”. what is the relief valve set at.
59.2 psi
63.7 psi
45.9 psi
77.7 psi
63.7
you have a system with a 35 hp motor and a 20 gpm pump. the cylinder diameter=3”, hydraulic tubing tensile strength is 55,000 psi, the steel tubing has a 3/4” outside diameter with a wall thickness of 0.109”. what is the maximum line pressure if it has a safety factor of 6.
2777
2664
5854
2864
2664
use the following information to calculate the effort needed. d=0.554”, D=3.25”, L= 3050 lbs, LD = 0.255”
74.4 lbs
66.6 lbs
88.6 lbs
59.2 lbs
88.6
what amount of torque is being produced if the system has a 25 gpm pump turned by a 1200 rpm electric motor and a hydraulic motor creating a pressure of 1770
113 ftlbs
75 ftlbs
243 ftlbs
413 ftlbs
113 ft/lbs
what diameter of cylinder will be needed to lift 5500 lbs with a pressure of 1000 psi
2.5”
2.75”
3”
3.25”
2.75
when troubleshooting a hydraulic system, you find a slow actuator acting against the full force in the system. the problem would not be
the pump wearing out
damaged seals in the actuator
flow control restricting to much
system relief valve set above pump operating pressure
system relief valve set above pump operating pressure
when troubleshooting a hydraulic system, you find to low of a pressure. it could be
pressure reducing valve set to low
pressure relief valve set to high
pressure relief valve set to low
both the first and 3rd answers are correct
Both first and third asnwers
if you have erratic movement in your actuators it is a sign of
erratic pressure
air in the fluid
no lubrication on machine ways or linkage
all the above
all of the above
if you had a hydraulic system that ws overheating and had excessive noise at the pump, the problem would likely be
fluid viscosity to high
excessive pump speed and load
dirty inlet filter
all the above
all of the above
if you found a hydraulic motor with a broken shaft, the problem could be caused by
system pressure overload
misalignment
failed bearing
all the above
all of the above
excessive heat in a hydraulic system could be caused by
proper fluid viscosity and proper oil
oil bypassing a filter
relief valve stuck partly open
both the 2nd and 3rd answers are correct
Both second and third answers are correct
o low of a flow rate and to low of system pressure could be caused by the relief valve setting being to low
true
false
True
excessive pressure in a hydraulic system would be caused by a pressure relief valve with a broken spring
true
false
False
valve issues found when troubleshooting can be any of the following. spool sticking, defective O-rings and a burnt out solenoid
true
false
True
invisible leaks on cylinders are between the piston and the cylinder wall and between the rod and cylinder wall
true
false
True
erratic pressure could be caused by a defective accumulator or one that has lost its charge of nitrogen into the fluid
true
false
true
the MAIN function of hydraulic fluid is to
transmit power from the pump to the actuator
lubricate moving parts
seal clearances
carry heat and contaminates away
Transmit power from the pump to the actuator
petroleum based hydraulic fluids are used most frequently because
low cost
readily available
good lubricating qualities
all the above
all of the above
water based fluids that are glycol - based should have the pump mounted below the fluid level because the weight of it is heavier than water
true
false
true
synthetic oils are being used more and more because they have
a high resistance to oxidation
a high viscosity index
longer life
all the above
all of the above
vegetable oils such as soy oil are used when there are environmental considerations to take into account
true
false
true
store hydraulic fluids so the fluid is protected from the elements and the environment is protected form the fluid
true
false
true
the baffle in a hydraulic tank
keeps oils separated
keeps the water from getting into the oil
allows the mixing of the additives
slows the fluid down
Allows fluid to slow down
the inlet filter should be about _____________ and have a _____________ for safety
100 microns, bypass
3 microns, bypass
100 microns, check valve
100 microns and bypass
the return line outlet should be ______________ the fluid level and the angle of the cut (of the pipe) should be___________ the path to the pump inlet
above, facing
below, facing away from
above, facing away from
below, facing
Below facing away from
to help save the environment from major spills, you can use level indicators and automatic shut-offs to control the amount of oil lost
true
false
True
water coolers are more efficeint than air coolers as they can control the temperature mor accurately
true
false
True
the breather cap on top of the reservoir allows atmoshperic pressure in to push on the oil when the pump is creating a vacuum
true
false
True
reservoirs that are vented use ___________________ to help push the oil into the pump
supplied air pressure
atmospheric pressure
no air pressure
all the above
Atmospeheric pressure
if you have a closed circuit reservoir, you would use about ______________ psi
10-15
5-10
1-3
25-50
1-3
a hdyraulic tank that has the pump mounted inside the tank is the
flat top
L-shaped
overhead stack
vertical mount
Vertical mount
about 80 % of hydraulic component failures are due to____________
contamination
lack of lubrication
leaky seals
industrial mechanic errors
Contamination
filter carts can
transfer oil to the reservoir
clean the oil
empty the reservoir
all the above
All of the above
the type of contamination that gets into the system from the outside is
built-in
ingressed
generated
wear related
Ingressed
a micron is equal to 1 millionth of a meter
true
false
true
when setting IOS cleanliness targets for a hydraulic system, you know they are being attained by
proper filter systems
using a portable partical counter
visually inspecting them
oil changes at frequent intervals
Using a portable particle counter
it is necessary to have a bypass valve on a filter to
protect the filter element from collapse
protect the system from not getting the proper amount of oil
protecting the pump from cavitation
all the above
All of the above
the pleated fiberglass filter is supported by
a diffuser layer
filter media
metallic mesh
none of the above
Metallic mesh
depth type media consists of __________________ that capture dirt
matrix of fibres
clay
charcoal
fullers earth
Matrix of fibers
all hydrauic systems should have a filter located in the
pressure line
return line
pressure line before the DCV
after the cylinder
Return line
beta ratio is the
efficiencey of the hydraulic system
efficiency of the pump
efficiency of the filter
volumetric efficiency of the pump
Efficiency of the filter
to select the proper filter for your system, you would use a filter placement chart or manufactures recommendation.
true
false
True
maintenance of hydraulic fluid would include
water contamination protection
heat protection
oxidation protection
all the above
all of the above
dynamic O-rings have the same amount of squeeze as the static O-rings
true
false
False
for every 10 degrees C above 60 degrees C, the oxidation rate
tripples
doubles
quadruples
none of the above
Doubles
O-rings in hydraulic systems can be used as dynamic seals
true
false
True
never add sealant to the first 2 threads (from the end of the pipe) as it could add contamination into the system
true
false
True
to help tighten a loose fitting high pressure lip seal, you could add loctite to the inside of the housing where the seal sits
true
false
True
always use emery cloth in a perpendicular motion (not spiral motion) around the shaft to help stop spiral leaks
true
false
True
an accumulators MAIN function is to
absorb shock
even out pulsations
protect against over-pressure
store pressurized fluid
Store pressurized fluid
you should NOT use a flared fitting in a _______________ environment
dirty
hot
slippery
high vibration
High Vibration
flareless fitting are used with
thin walled tubing
thick walled tubing
both the 1st and 2nd answer
noe of the above
Thick walled tubing
when tightening flared fittings (after tightening hand tight) use a flare (tube) wrench and tighten 1/4 turn for fittings under 5/8” and 1/8 of a turn for sizes over 5/8”
true
false
True
when troubleshooting a pump cavitation issue at the inlet, the pressures you will be looking at will include both vacuum and atmospheric pressures
true
false
True
when installing hydraulic hoses, make sure to ______________ to make sure they are installed properly
have a slight twist in the hose
no twist in the hose
the hose is stretched slightly
the hose has the fredom to whip around
No twist in the hose
if you see blisters in the outer rubber layer of a hose this tells you that
the oil has been over-heated
there is oil leaking thru the reinforcement
the iner-tube is comming thru the reinforcement
it is normal to have some blisters
There is oil leaking through the reinforcment
