190303gA Flashcards
Tracked Equipment Steering Fundamentals and Service- Part A
What is the traditional method of providing steering control for track type tractors?
steering clutch and brake to control power flow to each track
how is engine power transmitted to each track in a traditional method?
split equally between left and right tracks
what is cross steer?
used on downhill steering grades, to turn left, you disengage right clutch power. opposite controls
how do you make a machine turn left or right with a traditional method of steering
interrupt power flow to one track, ex disconnect left track to turn left
braking the track where power has been interrupted results in what kind of turn?
a sharper turn
greater braking force, the sharper the ______
machine will turn
how does the operator control the application of power and brakes to the tracks in a traditional method?
steering control lever which activates steering control valves
what holds the steering levers in their normal position?
springs acting on the linkage
what is the normal position of steering clutches and brakes on a non-modulated system,?
steer clutches engaged, brakes released.
how are the brakes applied in a non-modulated system?
with progressive application
at mid range of travel in a non-modulated system, what is happening with the steering clutches and brakes?
steer valve will be completely disengaged, brakes will not be applied yet
as the operator pulls on the steering control lever, what position are the steer and brake clutches in at the end of the lever pull?
brakes full applied, steer disengaged
what does depressing a brake pedal or moving the park brake lever to the lock position do in a non-modulated system?
make independent brake applications, hydraulically apply the brakes without releasing the steering clutches
what is spring applied/released in a non-modulated brake set up?
steer clutches: spring applied
brakes: spring released
characteristics of the steering clutches?
hyd operated, wet, multi-disc
what do the tangs on the outer circumference of steel clutch plates mesh with?
internal surface of the brake drum
what is spring applied/released in a transmission?
tranny clutches: spring released, hyd applied
where does the steering valve vent oil to when not in use?
the tranny sump
what allows power to be transferred through the plates and discs?
frictional force between the plates and discs
on a cross shaft steer control valve, where does the oil come in from?
either port, both ports are connected the same way due to the cross shaft
what type of brake is used in a non-modulated setup?
wet contracting band type, mounted over the brake drum
what is a brake booster used for?
provide additional force for brake application. reduces operator effort
on non modulated brakes, what is the normal position of the springs?
spring released, as the brakes would always be on on if it was spring applied
what kind of braking is used with a band type?
self energizing, efficient in both forward and reverse
how are the spring conditions in modularized steering clutches and brake assemblies?
both clutch and brake are spring applied by belleville springs, released by oil pressure from steer/brake valve
where does oil flow come from on a hyd system?
from the tranny charge pump or separate steering pump
what is a priority valve used for?
ensure steering and brake circuit has enough oil before the tranny/torque converter system.
on a modulated setup, what is the function of the steering valve?
provide operator control over the application and release of steer clutches and brakes
when the steering control lever is not pulled on a modulated system, what happens?
steer clutch springs apply clutch, no oil is going to the piston. brake valve prevents oil from going to brake booster. goes to tank. relief valve send oil back to cooler
how does the brake valve allow the operator to control braking force?
brake valve regulates pressure in accordance with steering lever (modulates)
oil level too high would create?
overheating
oil that is dark, gritty, or burnt means?
excessive oxidation
what is track sag exponentially proportional to?
undercarriage wear
what would bronze coloured particles in a filter indicate?
clutch failure
what would shiny steel particles in a hyd filter indicate?
pump failure
what would rubber contaminants in a hyd filter indicate?
seal or hose fault
how can you warm a system up to operating temp?
stall test
slipping brakes during a stall test will cause the machine to?
creep or veer left or right
during a stall test, can the brakes hold the machine while the transmission is in its lower speed ranges?
no
what is an indication of slipping steering clutches in a stall test?
speed higher than spec in all transmission ranges
operator is pushing material, they release the RH clutch to make a RH turn but the machine stops. what is the fault?
LH clutch failure
on a steering and brake hyd stem, what could low pressure with engine running at low idle indicate?
excessive leakage in system
does a non-modularized or modularized system have an easier time in removal and installation?
modularized is easier to remove/install
how can you clean all metallic components (except bearings and friction discs)
steam cleaned, mineral spirits (varsol)
what should you measure friction discs for?
warpage, cone, wear
how do you measure wear on a friction disc?
outside micrometer
when is bevel gear shaft service performed?
when the steer clutches and brakes are serviced
what do improperly adjusted linkage result in?
clutches that don’t apply or release properly
too short of a steer clutch linkage would cause?
clutch to fully release, but not fully apply
too long of a steer clutch linkage would cause?
clutch to fully apply, but not fully release
when are brake linkage adjustments made?
after the clearance is adjusted between brake band and drum
too long of a brake linkage would cause?
full brake release, but not fully apply
too short of a brake linkage would cause?
full brake application, not full brake release
2 types of common brake types used in steering clutch and brake equipped machines?
band type
multi-disc oil bath
steering clutches and brakes are released with the steering control levers in their normal position
T or F
False
caution must be taken when disassembling crawler tractor brake assemblies because they contain:
very strong springs
what can you use to check friction disc warpage and cone?
flat surface and feeler gauges
