Air Brake System Testing and service 190105E

Question 1

1. List nine (9) safety precautions that must be observed when working around air brake
equipped vehicles.
a)
b)
c)
d)
e)
f)
g)
h)
i)

Answer 1

a) Park vehicle on a level surface with wheels blocked.
b) Always wear safety glasses.
c) Exercise care when working around a running engine.
d) Drain air from the system prior to service.
e) Never disconnect lines or remove components when the system is pressurized.
f) Never adjust system pressure above manufacturer specifications.
g) Use caution when working around spring brakes.
h) Understand the air brake system you are working on.
i) A void inhaling dust from brake linings.

Question 2

2. When visually inspecting the compressor mounting security look for:
   a)
   b)

Answer 2

a) Cracked or damaged mounting brackets.

b Loose or missing fasteners.

Question 3

3. A properly adjusted compressor drive belt will have a maximum deflection of:
   a) 1/4 to 1/2 inch (6.4 to 12.7 mm).
   b) 1/2 to 3/4 inch (12.7 to 19.1 mm).
   c) 3/4 to 1 inch (19.1 to 25.4 mm).
   d) 1 to 1 1/4inch (25.4 to31.8 mm).

Answer 3

b) 1/2 to 3/4 inch (12.70 to 19.05 mm).

Question 4

4. If you discover excessive oil when draining the air reservoirs, the problem is likely:
   a) a faulty air dryer.
   b) a faulty governor.
   c) leaking compressor discharge valves.
   d) worn air compressor piston rings and cylinders.

Answer 4

d) worn air compressor piston rings and cylinders.

Question 5

5. CVIP specifications state that a vehicle could be put out of service if the brake
   chamber pushrod travel does not fall between:
   a) 1/2and 3/4inch.
   b) 3/4 and 1 inch.
   c) 3/4 and 1 ½ inch.
   d) 1 and 1 3/4 inch.

Answer 5

c) 3/4 and 1 ½ inch.

Question 6

6. When performing the air brake system governor cut-out, pressure warning and
   pressure buildup test, you found that the low-pressure warning device went off at
   70 psi (483 kPa). This means that the operation of the device is:
   a) acceptable.
   b) is going off at a pressure that is too high.
   c) is going off at a pressure that is too low.
   d) none of the above.

Answer 6

a) acceptable.

Question 7

7. The Alberta CVIP states that the vehicle compressor should build up from
   - ———to ———– within 3 minutes.

Answer 7

50 psi (345 kPa) to 90 psi (621 kPa) within 3 minutes.

Question 8

8. You are testing a vehicle with a governor cut-out pressure of 120 psi (827 kPa) and
   find that the governor cut-in pressure is 90 psi (621 kPa). The problem is a:
   a) worn compressor.
   b) misadjusted governor.
   c) faulty governor.
   d) faulty safety valve.

Answer 8

c) faulty governor.

Question 9

9. You are checking for supply circuit leakage in a tandem gravel truck that is towing a
   pup trailer. The primary service reservoir pressure drops 4 psi (28 kPa) and the
   secondary reservoir drops 10 psi (69 kPa) over a 2 minute period. You conclude that:
   a) the rate of leakage is acceptable.
   b) primary leakage is acceptable but secondary leakage is excessive.
   c) primary leakage is excessive but secondary leakage is acceptable.
   d) both primary and secondary leakage are excessive.

Answer 9

b) primary leakage is acceptable, but secondary leakage is excessive.

Question 10

10. A body-loaded truck showed a pressure drop of 6 psi (41 kPa) in the primary
    reservoir and 2 psi (14 kPa) in the secondary reservoir when the service delivery
    circuit was tested for leakage. You conclude that:
    a) the rate of leakage is acceptable .
    . b) primary leakage is acceptable but secondary leakage is excessive.
    c) both primary and secondary leakage are excessive.
    d) primary leakage is excessive but secondary leakage is acceptable

Answer 10

d) primary leakage is excessive but secondary leakage is acceptable.

Question 11

11. Pushrod travel for a properly adjusted cam-operated foundation brake should be

Answer 11

As short as possible without drag between the brake linings and drum.

Question 12

12. The angle formed between the brake chamber pushrod and the slack adjuster arm
when the brakes are applied should be:
a) 90°
.
b) 120°
.
c) never greater than 90°
.
d) never less than 90°
.

Answer 12

d) never less than 90°

Question 13

13. When performing an automatic emergency brake circuit test, you found that the
    primary air reservoir pressure dropped when the secondary air reservoir was drained.
    The most probable cause of this fault would be a leak in the:
    a) supply reservoir.
    b) safety valve.
    c) check valve in the primary reservoir.
    d) check valve in the secondary reservoir.

Answer 13

c) check valve in the primary reservoir.

Question 14

14. Dented or kinked air lines in the parking/emergency brake circuit could cause the
    spring brakes to _

Answer 14

be sluggish when applied and released.

Question 15

15. Opening the supply line of a fully charged tractor/trailer combination with the
    parking brakes released should cause:
    a) the trailer spring brakes to and
    b) the trailer supply valve to _________________ _

Answer 15

a) immediately apply

b) shut off air to the supply line between 60 psi ( 414 kPa) and 20 psi ( 138 kPa)

Question 16

16. Before you attempt to mechanically cage spring brakes, you should

Answer 16

inspect the spring

brake chamber for damage.

Question 17

17. Before you back off the brakes on units that have automatic slack adjusters, you must
    be sure to:
    a) remove the clevis pin.
    b) remove or disengage the adjustment pawl.
    c) loosen the clevis jam nut.
    d) depress the locking sleeve.

Answer 17

b) remove and disengage the adjustment pawl.

Question 18

18. Alberta CVJP states that a vehicle will fail inspection if the radial clearance between
the camshaft and bushings is:
a) 0.030 inch (0.76 mm).
b) 0.040 inch (1.02 mm).
c) 0.075 inch (1.91 mm).
d) 0.085 inch (2.16 mm).

Answer 18

d) 0.085 inch (2.16 mm).

Question 19

19. Camshaft axial play should not exceed:
    a) 0.030 inch (0.76 mm).
    b) 0.040 inch (1.02 mm).
    c) 0.075 inch (1.91 mm).
    d) 0.085 inch (2.16 mm).

Answer 19

a) 0.030 inch (0.76 mm)

Question 20

20. Removing material from the inside diameter of a brake drum results in:
    a)
    b)

Answer 20

a) reduced strength

b) reduced ability to dissipate heat

Question 21

21. Alberta CVIP states that an air brake equipped vehicle will be put out of service if the
brake linings are worn below:
a) 1/8 inch (3.18 mm).
b) 1/4 in (6.35 mm).
c) 5/16 in (8 mm).
d) 3/4 in (19.05 mm)

Answer 21

c) 5/16 inch (8 mm).

Question 22

22. Camshaft axial play is adjusted by

Answer 22

adding or removing shims between the slack

adjuster and its retaining snap ring.

Question 23

23. If the angle between the brake chamber pushrod and slack adjuster arm is incorrect,
you must:
a) adjust the slack adjuster.
b) replace the slack adjuster
c) adjust the brake chamber clevis.
d) replace the brake chamber.

Answer 23

c) adjust the brake chamber clevis.

Question 24

24. It is important to closely watch brake adjustment following a brake reline because:

Answer 24

brake chamber pushrod travel will increase more rapidly than normal as the brake
linings wear in to the brake drums.