Truck Frames Flashcards
Most medium- to heavy-duty vehicles use a _____________ frame consisting of two long rails connected by a series of cross members that keep the rails in alignment
ladder-type
The ____________ supports all of vehicle’s components; body, vehicle driveline, and all suspension equipment are attached to the frame
frame
Most common type of frame rail is __________, but I-beam and box channel can be used.
C-channel
Frames must be ___________enough to bend and twist in reaction to various forces without deforming as vehicle moves along the road.
flexible
Frames must be strong enough to carry ____________
components plus the load vehicle is expected to carry.
Frame rails reinforced with ________________when required.
L-plate, fishplate, or another C-channel fitted inside rail
When frame is loaded, one flange is subject to _____________and the other flange subject to ________________
compression
tension
All frame attachments should be made as close as possible to the ___________
neutral fiber.
What is RPM?
actual strength of frame; calculated from frame’s section modulus and its yield strength.
Frames made from mild steel yield strength of ________psi
50,000psi (345 MPa)
heat-treated steel yield strength of _________ psi
110,000+psi (758 MPa)
aluminum alloy yield strength of ___________ psi
60,000 psi (414 MPa)
Which has the highest yield strength: mild steel, aluminum, heat-treated steel?
heat-treated steel
_______________ frames are lighter than steel and I-beam shaped for increased strength.
Aluminum alloy
What is the function of frame cross members?
hold rails in alignment; can be box channel, C-channel, I-beam, or hat shaped.
Cross members are often _______ to allow passage of wiring, piping, other vehicle components
curved
_____________ can be U-bolts, fishplates, or resilient mounts.
Frame body attachments
___________ least recommended but most common method of frame body attachment
U-bolts
When U-bolts are used the body can move longitudinally unless _________________
outrigger mounts also used to hold it in place.
Resilient mounts are spring loaded or have an elastic component and are used when the ___________________
body is not flexible; allows frame to flex independently of vehicle body.
________________________ establishes service criteria for commercial vehicles including vehicle frames.
Commercial Vehicle Safety Alliance
What happens to a vehicle whose frame does not meet commercial vehicle safety standards?
It is removed from service until repaired
Types of frame damage:
sag, bow, twist, diamond, and sidesway
Frame damage can be in form of ____________ from road salt or from galvanic cells created by dissimilar metals in contact.
corrosion
Manufacturers insist frame straightening be done __________
cold
It is common practice in the field to use heat even though heat can severely reduce _____________________
yield strength of a frame rail.
Frame re-alignment performed with use of ___________________.
sophisticated computer alignment machines
Frame re-alignment can also be performed manually by _______________
taking precise measurements of frame and projecting them onto a flat floor.
Manufacturers forbid _____________ on heat-treated frames because yield strength can be reduced from 110,000 to 36,000 psi by excessive heat.
welding
Frame ____________ is a common practice to increase frame rail length to install longer bodies or extra equipment.
splicing
____________________ can occur when two dissimilar metals are in contact and an electrolyte is introduced between them.
Galvanic corrosion
Galvanic corrosion creates a situation where one metal becomes the __________ and the other the ________ of the resulting galvanic cell.
anode
cathode
