302Aa (Not Completed) Flashcards
T/F single hydraulic steering cylinders can be used on large equipment
False
A directional control valve can also be identified as?
Reversing valve
On articulating machines, what do we use to limit the maximum turning angle?
An external steering cushion, or stop
Why is hydraulic pressure in the steering cylinder(s) on articulating machines relieved or unloaded just as the maximum steering angle is reached?
To prevent excessive impact loads from being imposed on the steering cushions (stops)
What are two types of filters used in hydraulic systems?
Depth type and surface type
With a full-time power steering system, if the dump box is being raised at the same time that the wheels are turned and the engine rpm (pump rpm) and road speed are low, what may happen to steering speed?
The steering action may be quite slow.
After toe adjustment, what check should be done on tie rod ends?
Ensure the threaded portion is still completely inserted in tie rod split. No air gap
Before opening any part of a hydraulic system what are two safety precautions?
Ensure hydraulic system is depressurized at the tank and accumulators if necessary.
After hydraulic repairs why must the system be checked and properly calibrated if needed.
Depending on repair pressure could be too high or low possibly causing injury or damage.
One method of checking hydraulic cylinders without entering the Hydraulic system is?
A heat gun checking fitting temp and middle of the barrel temp
Upon inspection of equipment you notice there is a bolt missing out of a fastener for a pin what should you do?
Remove pin and check for integrity. Who knows how long the pin has bin loose for and could have damage resulting in pre-mature failure
During a simple visual inspection of a unit what types of potential problems are you looking for?
Frayed/crushed Hydraulic lines, scoring on cylinder rods, dust boots ripped or removed
A road test of equipment should not be performed unless?
You are familiar with the equipment and its operation, measuring devices and manufacturers specifications. As well often someone to give you a hand.
Before pressure and flow testing a price of equipment what should be done
Ensure you have manufacturers specs. Gauges are capable of handling the pressure and heat the unit will produce. Oil at the correct operating temp and proper level
A full-time power steering system is sometimes referred to as?
Hydraulic steering system or subsystem
List the components of a full-time power steering system
A reservoir, hydraulic pump, pressure control valves, priority flow control valves, steering directional control valves, hydraulic cylinder assemblies, steering cushion assemblies, and hydraulic oil filters
One or more pressure control valves may be used in a power steering system to either?
Limit system pressure thereby protecting the hydraulic pump and other components
Regulate the hydraulic pressure in a secondary hydraulic circuit
Cause hydraulic control operation to follow a certain sequence
Flow control valves can be used to?
Limit the flow rate of hydraulic oil into a particular circuit
Identify any five (5) of the steering systems mentioned in this module that are used on off-road machines with a rigid frame.
a) front wheel steering, with or without a wheel lean feature
a) rear wheel steering
b) four wheel steering: crab steering
c) four wheel steering: co-ordinated steering
d) combination steering: front or rear wheel, crab and co-ordinated steering
e) skid steering
A wheel loader uses an articulated steering system. The rear tires:
follow in the track created by the front tires.
A tractor-scraper uses an articulated steering system. The rear tires:
turn inside the track of the front tires.
An operator has a machine that can be steered in either a crab or co-ordinated
fashion. Which steering system should be used to provide the maximum amount of
flotation during operation?
A crab steering system allows each tire to travel in a separate path thereby providing
maximum flotation during cornering.
Some hydraulic oil reservoirs have a clean-out cover. This allows the service
technician to remove sediment that has settled to the bottom of the reservoir.
true
The hydraulic pump used to pressurize the steering system during normal operation is
generally belt driven.
false;
A full-time power steering system has no mechanical connection between the steering wheel (or joystick) and the turning wheels, or articulating frame sections.
true
Identify any six (6) of the general components used in a full-time power steering
system
a) a reservoir
b) a hydraulic pump
c) one or more pressure control valves
d) one or more priority flow control valves
e) a steering directional control valve
f) one or more hydraulic steering cylinder assemblies
The hydraulic oil reservoir provides a place where the hydraulic oil can cool and
where sediment in the oil can settle out of the oil.
true
Identify the two (2) general types of steering directional control valves.
a) hand metering units
b) spool steering valves
Hydraulic steering cylinders are generally single acting.
false;
Depth type filters are typically used to clean the hydraulic oil in a full-time power
steering system.
true
Identify the device that can replace the steering wheel traditionally used to steer a
machine.
A joystick, often with finger and/or thumb switch controls can be used to replace the
traditional steering wheel.
A motor grader can be equipped with a front wheel steering system as well as an
articulated steering option. During the cornering process, the front wheels turn at less
of an angle than the articulation angle.
false;
When a wheel loader has an articulated steering system the front section of the
machine is much shorter than the rear section of the machine. This causes the rear
tires to move inside the front wheel track when the machine is cornering.
false;
Rough terrain cranes tend to have a solid frame with a four wheel steering system to
increase the manoeuvrability of the machine during operation in restricted areas.
true
A low percentage of hydraulic system problems are related to the selection, care and NOTES
cleanliness of the hydraulic oil.
false;
Identify safety precautions that must be followed when working on and/or testing
steering systems in order to prevent personal injury.
The test process must not endanger any personnel in the vicinity of the machine NOTES
under test. The hydraulic oil must be allowed to cool to reduce the chances of
personal injury due to burns. The pressure in the hydraulic system must be released
before any hydraulic line or fitting is loosened and removed. Follow all safety
precautions identified by the manufacturer.
A visual inspection is the first stage of troubleshooting the hydraulic steering system.
true
Explain why infrared heat detection equipment is a valuable troubleshooting resource
when inspecting the hydraulic steering system
The hydraulic steering system can be examined while in operation. The infrared heat
detection equipment can be used without disconnecting hydraulic lines and fittings.
As you inspect a hydraulic steering system for signs of problems, you must check the
following types of components:
a) mechanical.
b) hydraulic.
c) electrical and/or electronic.
d) oil and oil filtration.
e) all of the above responses are correct.
all of the above responses are correct.
Operational tests of a hydraulic steering system can include a road test as well as
flowmeter and pressure tests.
true
Explain how you must prevent a machine with an articulated steering system from
pivoting while you work at or near the point of articulation.
The safety bracket must be pinned to both sections of the machine to prevent
accidental movement and the possibility of crushing injuries.
Identify the general types of equipment you would use when you are working on the
hydraulic steering system and are required to remove and replace component
Floor jacks and adapters as well as overhead cranes along with chains and slings are
required to safely move heavy steering system components.
Hydraulic components (lines, actuators, fittings) must be properly covered once they have been opened.
true
2 things must be done in order to hook up test equipment.
Thoroughly clean area and release any hydraulic pressure.
Quick couplers can have pressure behind the caps. T/F
True.
Once a steering problem has been identified, list the steps for disabling the machine.
1: Lock out power source.
2: Set park brake.
3: Chock one or more wheels.
4: Lock articulation point.
5: Release any hydraulic pressure.
Who provides the articulation lock?
The manufacturer. It is usually attached some where on the machine.
There may be several steering components that may require servicing. Name 3.
1: Steering knuckle and king pin.
2: Tie rods and tie rod ends.
3: Toe adjustment.
4: Articulation joint.
5: Hydraulic components removal and replacement.
6: Hydraulic pressure adjustment.
The tie rod does not need to be torqued as it is cone shaped and will clamp itself. T/F
False. The tie rod must be torqued as it will seat the cone.
What must be done after installing the tie rod?
The toe must be checked and adjusted as per manufacturer specs.
