Trailer couplers or “gladhands”
When trailer lines are crossconnected,
the trailer brakes will not work correctly
– the spring brakes may not release, the towing vehicle may lose air and the service brakes will not function properly.
What will occur if the supply line ruptures?
Rupture of the supply line (or an uncoupling of the supply line glad hands – Fig. 47) results
in a pressure drop in the supply line between the trailer-supply valve and relay emergency valve
. This triggers the emergency action of the relay emergency valve, placing the trailer brakes into emergency application.
When the emergency line loses pressure what happens to the tractor protection valve?
6.2.
The tractor protection valve will close automatically if air pressure is low (in the range of 20 to 45 psi). When the tractor protection valve closes,
it stops any air from going out of the tractor
. It also lets the air out of the trailer emergency line.
What does a trailer-supply valve do?
Trailer air supply control:
Pushing it in supplies the trailer with air, and pulling it out shuts the air off and puts on the trailer emergency brakes
. The valve will pop out and close the tractor protection valve when the air pressure drops into the range 20 to 45 psi.
What is the blue glad hand for?
Service gladhands are blue in color and used to
connect service air lines (also called control lines or signal lines) that carry air to foot brakes or trailer hand brakes
.
What is the emergency air line for?
Emergency Air Line.
The emergency line (also called the supply line) has two purposes. First,
it supplies air to the trailer air tanks
. Second, the emergency line controls the emergency brakes on combination vehicles. Loss of air pressure in the emergency line causes the trailer emergency brakes to come on.
What is the red knob for in a truck?
The yellow one controls brakes on all axles, the red is only for
trailer
, and the blue is only for the truck unit.
What will happen if the lines are crossed when you hook up to an old trailer?
A driver crosses the air lines when hooking up to an old trailer. … A If the trailer has no spring brakes,
you could drive away but you would not have trailer brakes
. “If you crossed the air lines, you could drive away but you wouldn’t have trailer brakes.
When the out or emergency position the red trailer air supply valve prevents the loss of tractor air pressure by closing ?
You push it in to supply the trailer with air, and pull it out to shut the air off and put on the trailer emergency brakes. The valve will pop out (thus closing the tractor protection valve) when
the air pressure drops into the range of 20 to 45 psi
.
When the tractor protection valve is opened it allows air to?
When the pressure in the supply line reaches 45 psi, the service line port of the tractor protection valve opens. This allows application
air pressure to travel down the service line to the trailer when a brake application is made
.
What color is the supply line on a tractor trailer?
Generally these lines are color coded where the service line is blue and the supply line is
red
. If the trailer connectors are not color coded, then both are usually black or silver and the emergency line will connect to the receptacle closest to the driver’s side on the front of the trailer.
In what position should the trailer supply knob be in when the trailer is unhooked?
When disconnecting from a trailer, you should: Put the
tractor at a 90 degree angle to the trailer
(or as close to 90 degrees as possible) Have the tractor lined up with the trailer.
What might happen if the trailer is too high when you try to couple?
What might happen if the trailer is too high when you try to couple? If the trailer is too low, the tractor may stike and damage the trailer nose; if the trailer is too high,
it may not couple correctly
. … If there is space something is wrong and the trailer would come loose very easily.
What happens to the air brake system if the blue line leaks or breaks while driving?
What happens to the air brake system if the blue line leaks or breaks while driving? Nothing happens immediately, but when you apply the foot brake, you will find that the
trailer brakes do not work
. Repeated application will reduce air supply to 60psi causing the low air warning light and/or buzzer to come on.
What color is the tractor brake?
The two push-pull valves — the
yellow
one for tractor brakes and the red one for trailer brakes – are awkward to release because they must be pushed hard and held before brakes are released.
Can you drive without blue Air Line?
Yes you can still drive the truck and trailer
but you will not have any brakes on the trailer.
What are two things are important to prevent rollover?
Two things will help prevent rollover:
keeping the cargo as close to the ground as possible, and going slowly while turning
. Keeping cargo low is even more important in combination vehicles than in straight trucks. Also, keep the load centered on your rig.
What is a bobtail tractor?
In the trucking industry, “bobtail” usually refers to a semi-truck driving without a trailer attached. This term can also be used to refer to a straight truck transporting propane gas. But in the aviation industry, a Bobtail Tractor is
a high-speed cargo tractor
.
What is off tracking mean?
Off track is defined as
someone or something who is not moving forward properly or who is not going in the right direction
. An example of a person who is off track is someone who was supposed to go to college but instead dropped out.
What are the air lines on a truck?
Air line hoses are
flexible tubes used to convey pressurised air
. They are commonly used for carrying a supply of compressed air to operate pneumatic powered systems, such as a road vehicle air brake system for large vehicles and a railway air brake system for railway carriages / locomotives.
What is a trolly brake?
The trolley valve, or trailer hand valve or Johnson bar, operates
the trailer brakes on a combination vehicle
. The trolley valve should only be used when testing the tailor brakes, and should never be used while driving. If you use the trailer hand brake while driving, you can cause the tailor to skid.
With both the red and yellow buttons pushed in,
charge the system to air governor cutout
.
Turn off the engine
.
Disconnect the service or control line
(blue) to the trailer, leaving the supply or emergency line (red) coupled to the trailer or suitable sealed dummy coupling.
What does it mean when the fifth wheel locking lever is not locked after the jaws close around the kingpin?
The fifth wheel locking lever is not locked after the jaws close around the kingpin. This means that:
A The coupling is not right and should be fixed before driving the coupled unit.
How do you make sure that the air lines are not crossed after coupling?
After you supply air to the trailer, make sure the air lines are not crossed and The trailer brakes are working. This is done by:
Applying and releasing the trailer brakes and listening for brake sounds
. … In normal driving, some drivers use the hand valve before applying the brake pedal to prevent a jackknife.
Which statement best illustrates the crack the whip effect?
Which statement best explains the “crack-the-whip” effect?
When you make a quick lane change or sudden movement of your steering wheel, the rear trailer tends to swing out. The force of the rear trailer becomes amplified, causing it to roll over (rearward amplification).
What would happen if the emergency air line between the tractor and trailer came apart?
You are
driving a combination vehicle when the trailer breaks away
, pulling apart both air lines. You expect the trailer brakes to come on and: A The tractor protection valve to close. … When the emergency line loses pressure, it also causes the tractor protection valve to close (the air supply knob will pop out).
What color is tractor protection valve?
The other is the tractor protection valve (TPV), located on the towing vehicle’s frame or body. The TPV is also called a towing vehicle protection valve. The TSV has
a red-colored
, eight-sided knob and is controlled by the driver.
What is the crack the whip effect?
The crack-the-whip effect occurs
when you make quick lane changes
. The result can make your trailer turn over and flip. The crack-the-whip effect is caused by rearward amplification, which can increase with trailer size and the number of trailers you tow.
How do you check if your trailer is to low or high before coupling?
Exit the cab and make sure the fifth wheel is below the upper coupler plate. Verify proper fifth wheel height. If trailer is too low,
use landing gear to raise the trailer height
.
When the trailer air supply control valve is pulled out or moved from the normal to the emergency position the tractor protection valve will?
1. the tractor protection valve control (trailer air supply control) will pop out or go from “normal” to “emergency.” EXPLANATION: The tractor protection valve keeps air in the tractor or truck brake system
should the trailer break away or develop a bad leak
.
What happens when the wheels of a trailer lock up?
The trailer will often continue to move in a straight line. The trailer may disengage. The trailer may swing around.
When you turn suddenly while pulling doubles which trailer is more likely to turn over?
4. When you turn suddenly while pulling doubles, which trailer is most likely to turn over?
The rear trailer
is twice as likely to turn over as the tractor.
When backing under the trailer you should?
6.1.
When backing a car, straight truck, or bus, you turn the top of the steering wheel in the direction you want to go. When backing a trailer,
you turn the steering wheel in the opposite direction
. Once the trailer starts to turn, you must turn the wheel the other way to follow the trailer.
What will happen if the trailer supply line is disconnected from the truck?
Trailer couplers or “gladhands”
When trailer lines are crossconnected,
the trailer brakes will not work correctly
– the spring brakes may not release, the towing vehicle may lose air and the service brakes will not function properly.
What are the red and blue lines on a tractor trailer?
The red line is the air line for the trailer’s emergency brake
. … The blue line is the air line for the trailer’s service brake. Connect these lines to the corresponding couplers and socket on the trailer before moving the trailer.
What are the blue and red glad hands?
Usually the glad hands ( connectors) are colour coded, red to red etc… but if not the supply ( RED) is normally on the driver side of the trailer , or rear of tractor.. The
Blue is called the ” service’ line
, it is used as a ‘signal” line to activate the trailer service brakes ( but not the PARK brakes)…
When coupling the proper position of the 5th wheel is?
When coupling, the proper position of the fifth wheel is:
Tilted Down towards the end of the tractor
. A trailer is most likely to jackknife when it is: Empty.
What is the emergency air line for?
Emergency Air Line.
The emergency line (also called the supply line) has two purposes. First,
it supplies air to the trailer air tanks
. Second, the emergency line controls the emergency brakes on combination vehicles. Loss of air pressure in the emergency line causes the trailer emergency brakes to come on.
What part of the kingpin should the locking jaws?
Question: Which part of the kingpin should the locking jaw close around?
A The shank
.
What causes air in brake system?
The brake system is actually designed to be air-tight, however, air can be drawn into the system if you are driving on worn-out brake pads or if there is a problem with the brake calipers or pistons. The solution to air in your brake system is
brake bleeding
, which is how we remove the air from the brake fluid.
What does the blue air line do?
As you can see in the picture above, the blue color hose, called service line, is
used to carry air to the brakes
. It is controlled by the foot brake on the trailer. The red one, called supply line or emergency line, is used to supply a steady stream of air to the air tanks.
What Colour is the emergency brake line?
What colour is it? Explanation: The
red
emergency line is common to both two-line and three-line braking systems.
