Machine Frames Flashcards
Frames are constructed from welded-together _______________
and ____________ sections.
plate steel
cast steel
Frames will likely fail at ____________ if the frame is
pushed past design limits
one of the welds
______________ machines have two-piece frames
Articulated
Excavators have an upper and lower frame held together
with a __________________.
rotex bearing
Frame inspection should be part of regular maintenance,
and focus should be concentrated on _________________
welds and threaded
holes.
Frames can be ________ and ________ to prevent recurring failures.
repaired and reinforced
Frames should always be covered with _______ to
prevent rust.
paint
Any welding repairs should not create stress risers by
________________________
angling and curving reinforcements.
Suspension systems allow movement between a machines
frame and _______________
its drivetrain.
_______________ gives the operator a smoother ride and keeps the tires or tracks engaged with the ground
longer.
Suspension systems
Some older and/or small machines will use springs for
suspension. Springs can be ________, ____________ or __________
leaf type, coil type, or rubber.
_______ springs are stacked up in shortening multiples and
held stationary at one end. The other end pivots in a
shackle, and an axle is held to the spring assemblies’ center
with U-bolts.
Leaf-type
______ springs can be for axle suspension but the axle needs
to have links to keep it in place.
Coil
________________ use a hydraulic piston, oil, and an orifice to
reduce spring oscillations.
Shock absorbers
A sprung axle usually has a set of two shock absorbers
mounted to it. The other end will be _______________
mounted to the frame.
Front axles on backhoe loaders and rear axles on wheel
loaders oscillate. This is a simple type of suspension that
allows the axle to pivot a few degrees on a _________ or __________
center pin or bolt
on trunnions.
Suspension cylinders act like _________ and shock absorbers
and are mostly found on trucks to give ________________ and
allow the machine to travel fast over rough ground.
springs
a smooth ride
Most suspension cylinders use ___________ for the spring
effect and _____________ for the damping action.
nitrogen gas
hydraulic oil
__________ must
be precharged to a certain pressure or to make the rod
extend a certain length.
suspension cylinders
How do you change ride height or level the machine?
Oil can be fed into or drained out of active suspension cylinders
Ride control is a form of suspension for backhoe loaders
and wheel loaders that introduces _______________ to the
head end of the boom circuit.
an accumulator
Scrapers have ______________that allow some movement
between the tractor section and the scraper section of the
machine.
cushion hitches
A load cylinder and linkage allows movement
between the frame sections, and an accumulator provides
______________.
spring action
Walking beam suspension can be found on the __________________
rear tandem
axles of articulated rock trucks
Walking beam suspension allows a few degrees of
oscillation between ____________
all four wheels.
In a walking beam suspension, travel is cushioned with
_____________, and axles are located _____________.
rubber blocks
with torque rods
Payload scale systems can use suspension components to
translate pressures into ________________
payload weights
______________ allow track frames
to pivot a few degrees, and track rollers may have a bogie
system to allow them to follow the underfoot profile.
Equalizer bars
What are some operator complaints related to machine frames and
suspension systems?
rough ride
noises
excessive oscillation
machine not level.
Diagnostic procedures start with knowing the system and a
_______________
thorough visual inspection.
Most suspension components that allow movement require
_______________
regular greasing.
How can adjustments be made to accumulator or strut
precharge pressures?
This requires a charging kit that
includes special tools.
