Truck Frames

Question 1

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

Answer 1

ladder-type

Question 2

The ____________ supports all of vehicle’s components; body, vehicle driveline, and all suspension equipment are attached to the frame

Answer 2

frame

Question 3

Most common type of frame rail is __________, but I-beam and box channel can be used.

Answer 3

C-channel

Question 4

Frames must be ___________enough to bend and twist in reaction to various forces without deforming as vehicle moves along the road.

Answer 4

flexible

Question 5

Frames must be strong enough to carry ____________

Answer 5

components plus the load vehicle is expected to carry.

Question 6

Frame rails reinforced with ________________when required.

Answer 6

L-plate, fishplate, or another C-channel fitted inside rail

Question 7

When frame is loaded, one flange is subject to _____________and the other flange subject to ________________

Answer 7

compression
tension

Question 8

All frame attachments should be made as close as possible to the ___________

Answer 8

neutral fiber.

Question 9

What is RPM?

Answer 9

actual strength of frame; calculated from frame’s section modulus and its yield strength.

Question 10

Frames made from mild steel yield strength of ________psi

Answer 10

50,000psi (345 MPa)

Question 11

heat-treated steel yield strength of _________ psi

Answer 11

110,000+psi (758 MPa)

Question 12

aluminum alloy yield strength of ___________ psi

Answer 12

60,000 psi (414 MPa)

Question 13

Which has the highest yield strength: mild steel, aluminum, heat-treated steel?

Answer 13

heat-treated steel

Question 14

_______________ frames are lighter than steel and I-beam shaped for increased strength.

Answer 14

Aluminum alloy

Question 15

What is the function of frame cross members?

Answer 15

hold rails in alignment; can be box channel, C-channel, I-beam, or hat shaped.

Question 16

Cross members are often _______ to allow passage of wiring, piping, other vehicle components

Answer 16

curved

Question 17

_____________ can be U-bolts, fishplates, or resilient mounts.

Answer 17

Frame body attachments

Question 18

___________ least recommended but most common method of frame body attachment

Answer 18

U-bolts

Question 19

When U-bolts are used the body can move longitudinally unless _________________

Answer 19

outrigger mounts also used to hold it in place.

Question 20

Resilient mounts are spring loaded or have an elastic component and are used when the ___________________

Answer 20

body is not flexible; allows frame to flex independently of vehicle body.

Question 21

________________________ establishes service criteria for commercial vehicles including vehicle frames.

Answer 21

Commercial Vehicle Safety Alliance

Question 22

What happens to a vehicle whose frame does not meet commercial vehicle safety standards?

Answer 22

It is removed from service until repaired

Question 23

Types of frame damage:

Answer 23

sag, bow, twist, diamond, and sidesway

Question 24

Frame damage can be in form of ____________ from road salt or from galvanic cells created by dissimilar metals in contact.

Answer 24

corrosion

Question 25

Manufacturers insist frame straightening be done __________

Answer 25

cold

Question 26

It is common practice in the field to use heat even though heat can severely reduce _____________________

Answer 26

yield strength of a frame rail.

Question 27

Frame re-alignment performed with use of ___________________.

Answer 27

sophisticated computer alignment machines

Question 28

Frame re-alignment can also be performed manually by _______________

Answer 28

taking precise measurements of frame and projecting them onto a flat floor.

Question 29

Manufacturers forbid _____________ on heat-treated frames because yield strength can be reduced from 110,000 to 36,000 psi by excessive heat.

Answer 29

welding

Question 30

Frame ____________ is a common practice to increase frame rail length to install longer bodies or extra equipment.

Answer 30

splicing

Question 31

____________________ can occur when two dissimilar metals are in contact and an electrolyte is introduced between them.

Answer 31

Galvanic corrosion

Question 32

Galvanic corrosion creates a situation where one metal becomes the __________ and the other the ________ of the resulting galvanic cell.

Answer 32

anode
cathode