Deck 32: Vehicle Chassis Frame

Question 1

If you do not grind the weld profile flush after making a weld repair to a truck frame,which of the following is altered in a way that can cause another failure?

A) section modulus is reduced through a given frame section
B) section modulus is increased through a given frame section
C) tensile strength is reduced through a given frame section
D) tensile strength is increased through a given frame section

Answer 1

B

Question 2

When diagnosing suspected frame misalignment,which of the following should be performed before projecting the frame measurements to the floor?

A) wheel alignment
B) check for matching wheels and tires
C) check for visible damage the axles
D) all of the above

Answer 2

D

Question 3

Which of the following would most likely be used as a frame for a linehaul truck?

A) ladder C-channel frame with 10.25-inch (260 mm)depth rails,crossmember braced
B) ladder C-channel frame with 13.50 (350 mm)depth rails,trunnion braced
C) ladder box-section frame with a 10.25 (260 mm)section and tubular bracing
D) ladder I-beam frame with 13.50 (350 mm)web and crossmember bracing

Answer 3

A

Question 4

When it is necessary to reinforce a C-channel truck frame rail,all of the following practices are recommended EXCEPT?

A) reinforcement material should match the tensile strength of the frame rail
B) reinforcement plates should be angled and radiused to avoid sudden changes in SM
C) reinforcements should be welded to the frame rail
D) reinforcements can be added to either the outside or the inside of the frame

Question 5

Technician A says that the section modulus (SM)of a frame member is a measure of its twistability.Technician A says that the higher the section modulus the more rigid a frame member is.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 6

Which of the following is true regarding about RBM (resist bend moment)as it applies to heavy truck frames?

A) product of section modulus and material strength
B) specifies frame flexibility
C) should be used stand-alone to spec frames because it factors both strength and flexibility
D) all of the above

Question 7

When it is necessary to drill into frame rails,all of the following practices should avoided EXCEPT?

A) drilling two holes in vertical alignment with each other
B) drilling two holes in horizontal alignment with each other
C) drilling in the flanges
D) marking drill locations with a steel scriber

Question 8

On a ladder type highway tractor frame,what components are referred to as the rails?

A) webs
B) the two longitudinal members
C) upper and lower flanges
D) the transverse members

Question 9

Which of the following welding practices is most likely to produce a crystallization failure on a repair of tempered frame rail?

A) welding too slowly
B) not allowing sufficient cooling time between weld runs
C) insufficient penetration
D) using a vertical-up welding technique

Question 10

What is the specified yield strength of a Class 8 truck frame with a tempered steel alloy frame?

A) 70,000 psi (480 MPa)
B) 110,000 psi (760 MPa)
C) 80,000 psi (550 MPa)
D) 140,000 psi (965 MPa)

Question 11

When reinforcing frame rails to support increased loads,what other factors should be taken into account?

A) suspension weight rating
B) axle weight rating
C) brake capacity
D) all of the above

Question 12

When it is necessary to repair-weld a damaged frame rail,on which of the following frames is it recommended that you clamp a "chill strip" on the opposite side of the area being welded?

A) tempered aluminum frames only
B) tempered steel frames only
C) mild steel frames only
D) both A and B are correct

Question 13

Which of the following on a highway tractor I- or C-channel frame rail is vertical?

A) flange
B) web
C) gusset
D) all of the above

Question 14

When you have to cut tempered frame rails to extend a frame,which of the following angles would be recommended?

A) 90 degrees
B) 75 degrees
C) 80 degrees
D) 60 degrees

Question 15

What is the function of the crossmembers that unite a pair of rails in a truck suspension?

A) provide a mounting point for chassis sub-components
B) limit the torsional forces a frame is subjected to
C) unite the rails so that forces are transmitted and shared between them
D) all of the above

Question 16

Technician A says that a tempered frame rail repair that has failed by cracking cleanly through the center of what visually appears to be a good weld could be caused by using the incorrect filler rod.Technician B says that cracks that appear at the sides of what appears to be a good weld on a tempered frame rail can be caused by crystallization.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 17

Which of the following terms describes the maximum stress a material can withstand without permanent deformation and damage?

A) yield strength
B) resist bend moment (RBM)
C) tensile strength
D) applied moment

Question 18

When selecting a welding method and filler wire or electrode to repair a cracked frame rail,which of the following must be considered?

A) minimizing loss of temper
B) avoiding crystallization
C) matching the filler wire or electrode to the rail material
D) all of the above

Question 19

When carrying very heavy loads is the primary consideration in choosing a highway tractor frame,which of the following would be the best choice?

A) deep-section,3/8" (10 mm)double rail,tempered steel frame
B) high-strength magnesium-silicon-aluminum alloy frame
C) non-fish-plated,middle alloy steel
D) pressed box-section ladder frame with drop-style crossmembers

Question 20

Which of the following truck frame materials has the highest yield strength?

A) copper-aluminum alloy
B) magnesium-silicon-aluminum alloy
C) mild steel
D) HSLA steel (high-strength low-alloy)

Question 21

When a fully loaded dump box is raised on a dump truck,which section of the frame is subject to the most stress during the process?

A) extreme front section
B) mid-section closest to PTO pump
C) mid-section closest to lift ram
D) extreme rear section

Question 22

Which type of frame damage is commonly caused by overloading?

A) sidesway
B) sag
C) diamond
D) twist

Question 23

Which of the following truck chassis components would likely have the highest section modulus (SM)?

A) I-beam frame rail
B) C-channel frame rail
C) cylindrical fuel tanker
D) unibody trailer van

Question 24

Technician A says that the RBM value of a frame is a measure of its ultimate rigidity.Technician B says that the RBM value of a frame is a measure of its ultimate strength.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 25

When Huck fasteners are used on a highway tractor frame,what SAE grade rating are they usually equivalent to?

A) Grade 3
B) Grade 5
C) Grade 8
D) Grade 10

Question 26

Technician A says that mild steel trailer frames can be welded using MIG welding equipment and general purpose steel filler wire.Technician B says that when extending a mild steel trailer I-beam ladder frame,the weld must be performed at a 45-degree angle.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 27

Technician A says that in some tanker trailer applications,the tank can be used as the primary frame,with sub-frames attached to the tank to mount the upper coupler and suspension components.Technician B says that a tank mounted to a straight truck with a ladder frame must be mounted in a way so that the frame moves independently from the tank.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 28

Which of the following AWS welding electrodes should be used to weld a tempered steel,truck frame rail?

A) E-6010
B) E-6011
C) E-7018
D) E-11018

Question 29

What is the term used to describe a frame bolt that is designed with an interference-fit shank?

A) over-size
B) body-bound
C) Grade 8
D) coach

Question 30

When a load is placed on a truck with a C-channel,ladder frame,which ONE of the following is true of the C-channel rails?

A) neutral fiber is under compressional force
B) upper flange is under tensional force
C) lower flange is under tensional force
D) the entire rail is under compressional force

Question 31

Technician A says that diamond frame damage is often caused when a ditched truck,is hauled out by attaching chains to just one side of the frame.Technician B says that twist frame damage can be caused by using a truck as a snowplow.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 32

A suspension mount bolt hole has become enlarged in a frame due to shear forces.What should be done?

A) replace the frame
B) drill oversize to the next bolt size up
C) ream oversize to the next bolt size up
D) grind a taper on the bolt and drive in

Question 33

When a truck with a C-channel,ladder frame is involved in an offset front end collision,one frame rail is moved slightly ahead of the other.What is this type of damage known as?

A) twist
B) sway
C) sidesway
D) diamond

Question 34

Technician A says that two truck frame rails with exactly equal RBMs,can have very different dynamic performance.Technician B says that highway tractors are required to have much higher section modulus (SM)than dump trucks.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 35

What is generally considered the best method when repair welding an aluminum alloy frame rail?

A) TIG
B) MIG
C) shielded arc electrode
D) oxy-acetylene torch

Question 36

Where is the neutral fiber of a C-channel frame rail located?

A) flanges
B) center of the web
C) at the C-radius
D) all of the above

Question 37

Technician A says that a low section modulus frame (SM)has the advantage of better ride,a desirable feature in highway tractors.Technician B says that keeping SM low and rail yield strength high,is one way of achieving a highway tractor frame that has a forgiving ride and high RBM.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 38

If a perfectly round hole was reamed into the neutral fiber of a truck C-channel frame rail and the rail was than subjected to a within specification load force from above,how would the hole be effected?

A) should remain perfectly round
B) elongate vertically
C) elongate horizontally
D) should reduce in size

Question 39

Technician A says that the a three-element frame rail can usually achieve a high section modulus (SM)without adding additional weight.Technician B says that one way of meeting a high RBM requirement and keeping the weight of a frame to a minimum is to use hardened steel frame rails.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 40

Technician A says that low hydrogen arc welding electrodes should be used when it is necessary to weld on a hardened steel frame rail.Technician B says that tempered steel rails can be MIG welded using appropriately rated wire in less time and lower risk of comebacks.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 41

Technician A says that the center of a dump truck frame at the lift ram mounting point is subject to the most stress when the dump box is fully raised.Technician B says that the front and rear of a highway tractor frame is subject to less stress than the remainder of the frame.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 42

Technician A says that when extending a tempered frame rail,the extension channel does not have to be tempered so long it is at the rear of the truck.Technician B says that when extending a tempered frame rail,either a 45- or 60-degree cut-angle is recommended to avoid a sudden change in RBM over a given vertical section.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B