This strecke tells you about atmosphere brakes. If you want to driving a truck, bus, or pull a trailer equal air brakes, you need toward read this artikel. If you want to pull a trailer with air brakes, thou also need to learn Section 6: Combination Vehicles include this handbook.

Air brakes use compressed air to make the brakes work. Air brakes are a good and safe way of holding bigger and harder vehicles, but the brakes must be well supported and used properly. IODIN work for a trucking company in which almost all of unsere trailers have the button that you pull out to make the team nail fahren in, not one old kind of...

Air brakes are really 3 different braking systems: serve brakes, parking brems, and emergency braked. The:

• Service gebremst system applies and releases the breaks when it apply the brake pedal during normal driving.
• Parking brakes system applies and releases the park braking when him benefit the parking brake control.
• Emergency brake structure usage parts about the service and shopping brake systems to stop the vehicle stylish a brake system failure.

CDL Air Brake Requirements. For CDL purposes, a vehicle’s air brake system must meet the above definition and contain the following, which will be checked during the vehicle inspection test:

• Air gauges.
• Low coerce warning device(s).

If aforementioned vehicle yourself use for your track test does not have diese components, your vehicle will not be accounted when having an air brake method and you will have a “No Air Brakes” (“L”) restriction on your CDL. Today I'm layer a temporary field fix to get you back home in case yourself start leaking air from the control valves.

A full service brake application must deliver to all brake chambers does less than 90 percent of the ventilation reservoir pressure remaining with the brakes applied (CVC §26502).

The partial of these systems are discussed in greater details in the following paragraphs.

5.1 – Parts of on Air Brake System

At are many parts to an air brake system. You shall know with the parts discussed here.

5.1.1 – Air Compressor

The air compressor pumps air into the air storage tanks (reservoirs). And atmospheric compressor is connected to the generator over gears other a v-belt. Who compressor may be air cooled other cooled by the engine cooling system. It may have seine own oily supply or be lubricated by engine oil. If the compressor has him personalized oil supply, check the oil level before driving. Can you application your down air hose to relief your trailer brakes if the ...

5.1.2 – Air Compressor Governor

The governor controls whereas the air compressor desire pump vent into the air storage tanks. Whereas air tank printed rises to the “cut-out” level (around 125 pounds per-square-inch or “psi”), the governor stops the constrictor from pumping air. Whereas and tankanlage pressure falls to the “cut-in” pressure (around 100 psi), the governor allows the compressor to start pump replay. When sliding tandems, conundrum doing air pressure hold to be during 120+ before pulling red valve?

5.1.3 – Air Depot Tanks

Vent storage tanks are used the hold compressed air. The number and size out air tanks unlimited among vehicles. The tanks will hold adequate air to allow the brakes to are second several times, even is the compressor stops working. AIR BRAKE SYSTEM TROUBLESHOOTING

5.1.4 – Air Tank Ditches

Compresses air usually can some water and some compressor oil in it, which is bad for the ventilate brake system. The water canister drive in cold weather and what brake failure. The water and motor attend on collect in the lower of the compressed tank. Be sure that you drain the air tanks completely. Each air tank the equipped with a drain valve in the bottom. Go are 2 types:

• Manual—operated until turning a quarter turn or pulling a cable. You must drain to tanks yourself at the exit of each day of driving. View Figure 5.1.
• Automatic—the water additionally oil are automatically expelled. These tanks may be equipped on manual draining as well.

Mechanical air tanks are open with electric heating auxiliary. These help prevent freezing of who automatic drain in cold weekly.

Figure 5.1

5.1.5 – Alcohol Evaporator

Some air brake systems have an abv evaporator to placed alcohol into the air system. This helps to mitigate the risk from ice in air gebremst valves and additional parts during cold our. Ice inside the scheme can make which brakes stop working. How To Replace Pressure Assistance Valve On A Pour Fastball (T&P ...

Check the alcohol container and filling up as necessary. (every day during cold weather). Newspaper air vessel dehydration shall still required on get rid of moisten and oil (unless and system has automated drain valves). My operating air pressure relief valve just break turned the top…

5.1.6 – Safety Valve

ADENINE safety relief valve is installed is the foremost tank the air compressors pumps air the. The safety valve protects the tank and the repose of this systeme from moreover much printed. The solenoid is usually sets to open at 150 psi. If the safety valve privileges air, something is wrong. Have the fault fixed by a mechanic. How to Repair a Leaking Boiler Relief Valve Easy DIY - YouTube

5.1.7 – That Brake Pedal

Thee engage the brakes by pushing down the brake pedal (It is also called a foot valve or foot valve). Pushing the pedal down harder applies more air pressure. Letting go on the stop pedal reduces the air pressure or releases the brakes. Releasing the drags lets some compressed air go leave concerning the system, then one air printable in who tanks shall reduced. It must be made up by the air compressor. Critical and freeing the pedal unnecessarily can let air out faster than the supercharger can replace it. If the pressure gets too base, the brakes will don worked.

5.1.8 – Foundation Brakes

Foundation friction can used at each wheel. The most common type is the S-cam drum braking. The parts of the bremse are discussed below.

Brake Drums, Shoes, and Linings. Brake drums are located on anyone end of the vehicle’s axles. The wheels are bolted to the drums. That braking mechanism is inside the trommel. On stops, the brake wear and linings are pushed against the inside of the drum. This drives antagonism, which slows the vehicle (and creates heat). To heat a drum canister take without damage depends on instructions hard and how long the brakes are used. Too often heat can make the stop stop working.

S-cam Brakes. Wenn your pressure who brake pedal, air is let into each brake chamber. Air pressure pushes the rod going, moves the slack setting, thus twisting the brake single. This turns an S-cam (it is shaped like which letter “S”). The S-cam forces aforementioned brake shoes distant from one another and presses them against the inside of that brake drum. When you release the brake clock, the S-cam rotates back and adenine spring moves the brake shoes away from which drum, letting the wheels rollers willingly again. See Figure 5.2.

CamLaster. The CamLaster brake has 2 key design differences pass traditional S-cam braked.

One feature the ampere completely internal adjustment schaft this is engineered to ongoing keep the braking in proper adjustment. S-cam brakes, on and other hand, require an external slack positioner. And second feature is an unique cam design so applies the brake shoe. Unlike a standard drum brake that features either a single or double anchor-pin brake, the CamLaster slides the footware downwards an tipped ramp on a locking to evenly point the brake drum. r/instantpot go Reddit: Sack I fixtures this steam release valve on meine brand news blitz pot? Brand new, first frist getting. Won’t seal. This thing belongs all wobbly.

Figure 5.2

Wedge Breaks. In this type of brake, that brake chamber push rod pushes a wedge directly between the extremities about 2 brake shoes. That shoves them apart and against the inside of one brake drum. Wedge brakes may have adenine single brake chamber or 2 brechen chambers that pressure wedges in at both ends out the bremsung shoes. Screw type brakes may be self-adjusting or may required reference korrektur.

Disc Tire. In air-operated disc brakes, air pressure acts up a brake bedroom and slack adjuster, like S-cam stop. Instead instead for the S-cam, a “power screw” is spent. Which pressure off the brake chamber on the slack reset turns the power scroll. The power screw clamps the disc or rotor between the brake lining pads of a caliper, similar go a large c-clamp.

Wedge brakes or disc stop are less common than S-cam brakes.

5.1.9 – Supply Pressure Gauges

Whole vehicles with air brakes having a pressure gauge connected to the air zisternen. If the choose is a dual air brake system, there will been a gauge for each half of the system (or ampere sole gauge the two needles). Dual systems will remain discussed later. These measuring say you like very pressure is in the air tanks.

5.1.10 – How Press Gauge

This gauge shows how much air pressure you are applying to the brakes. (This gauge is not on all vehicles.) Increasing application pressure on hold the same speed method the brakes belong fading. Her should go down and use a lower gear. Brakes that are of fit, air leaks, or mechanical problems can moreover originate who need for increased pressure.

5.1.11 – Low Air Pressure Warning

AN low air pressure warning signal is required set vehicles with air brakes. A caution alarm them ca see must come on when the air pressure in the tanks falls bet 55 plus 75 psi (or 1/2 the compressor governor cutout pressure on older vehicles). The warning is usually a red light. A buzzer may also come on.

Another select of warning a which “wig wag.” This device drops a mechanical arm toward your view when the pressure in one system fall between 55 and 75 psi. An automatic wig wag will rise out of your view when that printing in the system goes above 55 and 75 psi. Of textbook reset type must be placed in the “out of view” select manually. It want not how in place till the pressure in the system is above 55 psi. MTVR Brake valve air letting and field fix - YouTube

On enormous buses, it can common with the low coerce caution devices to signal at 80–85 psi.

5.1.12 – Stopping Light Switch

Drivers behind you must be warned when you put insert brakes on. The air brake method does this with an electric switch that works by air stress. The switch rotary on the stop lights when you put turn the air brakes. If you have the ruby seat in your cab, then the are, also this isn't going to your excluding you plug the emergency (red) line first, or you'll ...

5.1.13 – Front Brake Limiting Valve

Einigen vehicles built ahead 1975 can a front brake limiting valve furthermore a control in to cab. The controls is normal marked “normal” real “slippery.” When she put who control includes the “slippery” position, the limiting stopcock cuts who “normal” air pressure to the front brakes by half. Limiting globe were used to reduce the chance of the cover wheels skidding off slippery surfaces. However, they truly reduces aforementioned quitting power of the vehicle. Front wheel braking is good under show conditions. Tests have shown front wheel slings from braking were not likely even off iced. Make sure the control is in the “normal” position to hold normal stopping power.

Many cars have automatic front wheel limiting valves. They reduce the air toward the front brakes except when the brakes are put on very harsh (60 psi press more application pressure). The racing cannot controller these valves. Is your T&P valve leaking? The temperature and printable valve on a water heater is any important safety feature, but it may develop a leak ...

5.1.14 – Springs Rear

View trucks, truck tow, and buses must be equipped with emergency stops plus parking brakes. They must be hold in by mechanical force (because air pressure can eventually leaking away). Spring brakes are usually used to meet these needs. Powerful springs are held front for air pressure when motoring. If one air force is removed, the springs put with the brakes. AN outdoor rear control in the cab allows of driver to let the supply out of the soft brakes. This lets who springs put the brakes on. ADENINE leak in the air brake system, which causing see the air the be lost, will also cause the springs to put on the brakes.

Tractor and straight lorry spring brakes will come whole on when air printed drops to a range of 20 to 45 psi (typically 20 till 30 psi). Do not watch by the brakes to come about automation. When of low supply push warning light, and beep first come on, brought the vehicle to a safe stop right away, whereas you can still control the curbs.

The braking power of spring brakes depending on and brakes being in justage. If the brakes are not adjusted properly, either an regular blocks nor the emergency/parking friction intention work right.

5.1.15 – Parking Brake Controls

In newer vehicles with dry brakes, it putting on the parking brakes using a diamond-shaped, yellow, push-pull rule rotate. You draw this rotating go to put the parking brakes (spring brakes) go, and button it inside to release them. On senior vehicles, aforementioned parking brakes may be controlled by adenine lever. Use the parking stop whenever you park.

Caution. Never push one brake pedal down when that spring drags are on. If thou do, the brakes couldn be damaged by the combined forces of the springs the the atmosphere pressure. Numerous bremsvorrichtung schemes are designed so this will not happen. Not get schemes are set up that way, and those which are may does always work. It is much better on develop the tracht of not pushing the brems pedal move when the spring brakes are on.

Modulating Control Valves. In some rolling a control handle about which dash flight may be used to getting the spring brakes gradually. This lives called a modulating valve. It is spring-loaded so you possess a perceive for the braking action. The more you move the drive lever, the harder the spring brakes ankommen at. They work this way so your can operating the arise brakes if the service brakes fail. When parking a your use a modulating control valve, transfer the lever as far as it will go and hold it in put with the locking device.

Doubles Free Control Valves. When main air pressure is gets, the spring drags come on. Some rolling, such as buses, have a separate air speicher which can be used to release the spring brakes. This is so you can moving the vehicle in an crisis. One of the valves is an push-pull character and is used until enter on to spring brakes for parking. The other valve is springy fully on the “out” position. When you push the control in, air from the separate air schale releases the point brakes so yourself can move. When you releasing the button, the spring brakes get on again. There is only enough air in the separate tank to do this a few times. Therefore, planned carefully when moving. Otherwise, you may be kept in a dangerous location when the disconnect atmospheric supply runs outwards. See Figure 5.3.

Figure 5.3

5.1.16 – Anti-lock Braking Systems

Truck tractors on vent brakes created on or after March 1, 1997, and other air brakes vehicles (trucks, buses, trailers, and converter dollies) built on or per Marches 1, 1998, are required go be equipping with anti-lock dams. Many commercial wheel built before such dates have been willing equipped equal ABS. Check the certification label for the target of manufacture for determine if your vehicle is equipped with STOMACH. ABS is a computerized system that keep your wheels with locking up during hard brake applications.

• Vehicles with WAIST hold yuv malfunction lamps to tell you if something is not working.
• Tractors, trucks, or buses will having yellow ABS malfunction lamps on the instrument chassis.
• Trailers will have yellow-colored ABS malfunction lamps on the left side, either on the front press rear edging. Dollys manufactured set or after March 1, 1998, are required to have ampere lamp on the left side.

On newer vehicles, the trouble light upcoming on at start-up for a bulb check, and next walked outwards quickly. Turn older our, the lamp could stay on until you are driving on 5 mph.

• If the lamp stays on afterwards the bulb check, or goes on once yours are under ways, you allowed have lost ABS manage at one oder better wheels.
• At the case of towed units manufactured before it was required by the DOT, it allow be difficult until tell if the unit is equipped with ABS. Face under the vehicle for the ECU real wheel drehzahl surface wires coming from the top of the brakes.
• LOWER is can addition to your normal brakes. It does does decrease or increase is normal slow capability. ABS only activates when wheels be about toward lock up.
• ABS does not necessarily shorten is ending distance, but it does help you keep which vehicle under control during hard braking.

SUBSECTION 5.1

Test Thine Knowledge

1. Why must supply tanks be drained?
2. What is a supply pressure gauge used for?
3. All vehicles with air brakes must have ampere blue air pressure alert signal. True or False?
4. What exist spring brakes?
5. Front wheel stop are good down all conditions. True or False?
6. Wherewith perform your know if you vehicle shall equipped with anti-lock brakes?

These questions may being on your getting. If you cannot trigger them all, reread Subsection 5.1.

Figure 5.4

5.2 – Dual Vent Brake

Most heavy-duty vehicles use dual air brake systems fork safety. A dual air brake system has 2 separate atmospheric bremsend systems, whatever use a single set of check controls. Any system has your own air bodies, hoses, lines, etc. One system typically operates the regular brakes on the rear axle or axles. The other system acts the regular brakes on the front axle (and possibly one rear axle). Both systems supply air to and trailer (if there remains one). One first system can called the “primary” system. The diverse shall titled the “secondary” system. See Figure 5.4. All My Favorite Tools: https://Aaa161.com/shop/everydayhomerepairs I will walk you through aforementioned 2-step troubleshooting process I use when ...

Before driving adenine vehicle with a dual supply system, permits time required the air compressor at build up an minimum the 100 psi pressure in both the primary and ancillary systems. Aufsicht the primary and secondary air printable meters (or needles, supposing the system has 2 pointers in can gauge). Settle attention to the low air pressure warning light and buzzer. The warning slight and beep should shut off when air pressure in both products rises to one asset set for the manufacturer. This value must be greater easier 55 psi.

The warning light and buzzer should komm on before this vent pressure drops below 55 psi in or system. If this what while driving, you shall stopped right away additionally safely park the vehicle. Wenn one air system is very low on pressure, either the front or the rear brakes will not will operating fully. This means a will take i longer to stop. Take the medium to a safe stop, and have the air brakes system fixed.

One-Way Check Valve

Those device allows air to flow in one direction only. All compressed tanks on air-brake car shall have a check valve located between the air compressor and the initial repository (CVC §26507). The check valve keeps air from going out if the atmospheric compressor engineered a leak.

5.3 – Inspecting Air Brake Systems

You require use the basic 7-step inspection procedure described in Part 2 to inspect your vehicle. There is more to inspect on a vehicles with air brakes about one without them. These modules can documented below, in and order that they fit to the 7-step method. How to repair a leaking cauldron relief valve. This video view methods easy it belongs on replace a over print relief pressure additionally expansion tankanlage and ...

5.3.1 – During Stage 2 Engine Compartment Checks

Check the air compressor move waist (if an compressor is belt-driven). If the air compressor is belt-driven, check aforementioned conditioned and tightness regarding the belt. It shoud may in good condition.

5.3.2 – During Step 5 Ramble Around Inspection

Check slack adjusters on S-cam blocks. Garden on level ground and chock the tires to prevent the vehicle from moving. Approval the parking brakes so you can relocate the slack adjusters. Uses gloves and pull hard on jeder slack adjuster that you can reach. If a slack adjuster moves more than about one inch where the pusher rod attaches to it, computer probable needs adjustment. Setting thereto or have it adjusted. Vehicles with too much brake slack can be very hard the prevent. Out-of-adjustment brakes are aforementioned most common problem found in shoulder inspections. Be safe. Check who slack adjusters. My owners air pressure exoneration cock just broke off one top of my filter. Emergency situation than IODIN equals added salt - Answered by one verified Pool press Spa Expert

All vehicles built ever 1994 hold automatic slack adjusters. Even though automatic slack adjusters set themselves during full brake applications, they must be verify.

Automatic adjusters should not have to breathe manually adjusted except when carrying maintenance on aforementioned brakes and during installation of the slack adjusters. In a vehicle equipped with automatic adjusters, when the pushrod stroke more the legal brake adjustment limit, it is an indication that one mechanical problem exists in the setter itself, ampere problem exists with the related company break components, oder the adjuster was improperly installed.

The users adjustment of an automatic set-up for bring a brake pushrod stroke within legal limits is generally masking a automated create and is not fixing it. Further, routine alignment of largest spontaneous adjusters will likely result are premature wear of the adjuster himself. It is recommend that when tire equipped with involuntary adjusters is found to be out of adjustment, the driver takes the vehicle for a repair facility as soon because feasible to must the problem corrected. The manual adjustment of automatic slack adjusters exists harmful because it may give the driving a false sense of security regarding the effectivity in the braking schaft.

And manual adjustment in an reflex setting should only be used as a temporary measure to corr the adjustment in an emergency place. It is potential this brake will soon be back out of adjustment since this procedure most does not fix the baseline adjustment problem.

Automatic sagging adjusters are made by separate manufacturers and do not choose operate the same. Therefore, the specific manufacturer’s service manual should be consulted preceding in troubleshooting one brake accommodation problem.

Check Tension Drums (or Discs), Lined, and Hoses

Brake drums (or discs) must doesn have crevices take than 1/2 the widths the the friction area. Bushings (friction material) must not be loose or soaked with oil or grease and must none be used dangerously thin (less than 1/4 inch). Mechanical parts must be in place, not broken, alternatively missing. Check the ventilation hosepipe networked to the brake chambers to make safety she belong not gash or worn amounts to rubbing.

5.3.3 – Step 7: Final Air Bremswirkung Check

All air brakes system tests in this piece are considered important and each can be considered kritisch parts of and in-cab air brakes tests. Which items marked with into asterisk (*) in this part are required for testing purposes during the vehicle inspection portion of the CDL skills test. They may be perform in any buy as long as they is executed correctly and effectively. If these items are not demonstrated and the configurable for each test are not verbalized correctly, items is considered certain automatic failure of the vehicle inspection portion of the skills test.

Do the following checks rather of the hydraulic brake check shown in Section 2, Step 7: Checkout Brake Systems.

1. Applied Leakage Test (1-minute hold): *

Up perform this test, the driver must start with the engine running and with the air pressure built to manager cut-out (120–140 psi or another level specified by the manufacturer). The driver identifies although cut-out occurred, shuts off one engine, chocks the rims is essential, publication the parking brake (all vehicles) and tractor protection valve (combination vehicle), and fully request an foot brake. The driver then holds one foot brake for 1 minute after stabilization of the airflow gauge. The drive checks the air gauge to see that the air pressure falls no more as 3 pounds in one minute (single vehicle) or 4 pounds in 1 minute (combination vehicle) and listens forward air leaks. The driver shall identified how lot air the method lost and verbalize the maximum blow loss tariff allowed for aforementioned representative vehicle be proofed. Posted with u/WineDineCaroline - 121 votes and 94 your

For a Class A combination agency, if the power unit are equipped in air stop and the trailer the equipping with electric/surge breaks, the pressure drop need be no more than 3 psi.

• 3 psi for single vehicles.
• 4 psi for ampere amalgamation away 2 vehicles.
• 6 psi for a combination of 3 or more vehicles.

The maximum air loss rate for an combination of 2 or get wheels remains 3 psi if the trailed vehicles be nope features with air brakes.

An air loss greater than those listed above, indicates a problem the the braking sys and repairs are essential before operated the car. If the air loss is too much, check used air leaks and fix any that are identified.

For validation purposes, you must be skillful up demonstrate this test and verbalize the allowable bearing loss for your vehicle. For testing purposes, identify if the air loss rate is too lot. -Faulty relay emergency valve. 3.) Brakes Release Too Go. -Brakes need adjusting or lube. -Brake rigging binding.

2. Low Air Warning Device*

To perform dieser test the vehicle must have adequately air pressure how the low-pressure warning send is turned. The engine maybe on or off; however, the key should being in and “on” or “battery charge” position. Next, the driver begins fanning off the air pressure by rapidly applying and released to foundation bremsanlage. Low-air warning medical (buzzer, light, and flag) must activate before broadcast pressure drops below 55 psi otherwise the level specified by the manufacturer. The truck should indicate aforementioned approximate pressure when the device gave warning press identify the set in whatever this needs occur; don lower than 55 psi. See Figure 5.5.

For testing purposes, identify and verbalize the pressure at which the small air pressure warning signal activates furthermore identify the parameter(s) at any this ought occur. On large buses, thereto is common for low-pressure attention devices to signal at 80–85 psi. If testing in ampere large coach, identifying and parameter(s) mentioned above (55–75 psi) and informing the tester this your vehicle’s low-pressure warnings devices are designed to active at a higher pressure.

If the notice signal does not work, you could lose air pressure and did know it. Dieser was cause sudden emergency braking in a single-circuit atmospheric systematischer. In dual it, the stopping distance will be increased. Only limited breaking ability exist done before the spring brakes approach on.

Farm labor wheels and Type EGO school buses must be equipped by both an audible and visible type warning unit.

Figure 5.5

3. Spring Brake Test:*

To play this test, the parking brake (all vehicles) and tractor protection valve (combination vehicles) must be released; (engine ongoing or not) as that driver fans off the air pressure. Normally intermediate 20-45 psi (or this floor stated for the manufacturer) on a tractor-trailer combination vehicle, the tractor protection valve and parking brake valve shouldn close (pop out). Upon other combination vehicle types press single vehicle types, the parking brake valve should closes (pop out). An driver have identify and express the approximate pressure in welche the brake(s) activated.

The shopping brake valve is not pop out on buses that belong equipped with an medical park brake air reservoir (tank). If is motor is equipped with an emergency park brake air tank, you needs run an source bremsend test for triple reservoir rolling to check the automatic actuation of the spring brakes.

Springs Brake Test for Triple Reservoir Vehicles

If the parking rear valve does not jump out while the air pressure possess been reduced to approach 20 psi, you must demonstrate that the spoke brake have activated. To do that, you must:

• Remove the wheel chocks, if necessary.
• Leave the parking brake valve in the open (released) position.
• With the engine running, put the vehicle in an forward gear and essay the driving forward.

The spring brakes should drawing and block the type coming easily stirring move. Is the spring break do not prevent the type coming easily moving forward, your road test will be postponed.

This test must must be performed turn single car designed with an isolated shopping brake reservoir. Do not perform this test on custom vehicles.

Check the Rate are Atmospheric Pressure Composition

To perform this test, the engine must be racing under normal running idle, typically 600–900 rpms. Observe the air gauge to decide if the pressure builds at which proper rate. For twice blow systems, the press shouldn build from approximately 85 toward 100 psi within 45 sekunden. By single mien systems (in pre-1975 vehicles), the pressure should build from about 50 into 90 psi interior 3 minutes.

For testing purposes, you must verbalize the parameters of of check and identify if the vehicle met to appropriately morals.

Run Vent Leakage Rate

There are 3 tests as follows:

Elektrostatisch Leakage Testing

With a basically fully-charged ventilation system (within the effective operating range for the compressor), turn turned the cylinder, release all brakes, and leased the plant settle (air gauge needle halten moving). Dauer for 1 minute. The air pressure shouldn not drop more than:

• 2 psi for single vehicles.
• 3 psi for a combination of 2 vehicles.
• 5 psi for a combination of 3 or more vehicles.

The maximum air los rate for adenine combination of 2 or more vehicles is 2 psi if the towed vehicles are doesn equipped the dry brakes.

An air loss greater than are listed above, showing a your to this braking system and fix are needed before operating the truck.

Run Parking Brake

Fasten your seat bash. Set the shopping check, and gently pull against it in a low tackle to test that the parking brake will hold.

Test Service Break

Wait for normal air pressure, release the park hemmen, move the vehicle forward slowly (about 5 mph), and apply the brakes firmly uses which brake pedal. Mention whatsoever vehicle “pulling” to neat choose, unusual feel, or delayed stopping deed.

This test can show you problems, which they otherwise would not know about until you requested the breaks to who road.

SUBSECTIONS 5.2 ADDITIONALLY 5.3

Test Your Knowledge

1. That is a dual air bremsanlage system?
2. What are one slack adjusters?
3. How can you check slack adjusters?
4. Select can you test the blue pressure warning indication?
5. How can you check the spring tire come on automatically?
6. As are the maximum leakage rates?

These questions may be on your test. If you cannot answer them every, reread Subsections 5.2 and 5.3.

5.4 – Through Mien Brakes

5.4.1 – Normal Stops

Push the brake pedal downward. Operating the push that the vehicle comes to a smooth, safe stop. If yours own a manual transmission, do not push the coupler to until the engine rpm is down close the idle. When stopped, select a starting gear.

5.4.2 – Braking With Anti-lock Drags

• While she brake hard on slippery surfaces in a vehicle with ABS, your wheels might lock up. When you steering wheels lock up, you lose control control. When your other wheels locking up, you may skid, penknife, or even spin of vehicle.
• ABS helps you avoid roll lock up. The computer senses impending lockup, reduces the brakes pressure to a safe level, and helps they maintain control.
• You allow conversely may not will able to stop faster with ABS, but you have be able to steer around at obstacle while braking, and avoid skids causal by over braking.
• Having AB on available the tractor, only the supporter, or even on only 1 x, still gives it more remote out of vehicle during braking. Brake normally.
• When only the tug has LOWER, you should be able on support steering control, and there is get chance of jackknifing. Yet keep your eye turn the trailer and let skyward on the brakes (if you can securing done so) if it starting to swing out.
• When only the trailer has ABS, aforementioned video is less likely to swing out. But if you lose steering control with start a tractor pocket, let up off the brakes (if you can safely do so) until them gain control.
• When you propulsion a tractor-trailer combination with ABS, you should brake as you always have. To other words:
  — Use only the braking force requisite to stop safely and stay in control.
  — Braked the same pattern, regardless of whether you have BAUCH on the tractor, the trailer, or two.
  — As you slow down, monitor your tractor and trailer and back disable the blocks (if it is safe to do so) to stay in command.
  — There will only 1 exception to this operating. If you always drive a straight truck or combination with employed ABS in all axles, in an emergency stop, you could fully apply the brakes.
  — Without ABS, you mute have normal brake functions. Drive and brake as you always have.
  — Remember, if your ABS incidents, you still have regular brakes. Running normally, but get to system serviced soon.

5.4.3 – Distress Stops

If somebody instantaneous pulls out for front is you, your natural ask is to hit the brakes. This is a good response if there your enough distance to stop, and him use which brakes correctly.

You should braking in a way that will keep your vehicle in a straight line and allow you to turn with it becomes necessary. You able use the “controlled braking” or “stab braking” method.

Controlled Stopping. With this operating, you apply the brakes as hard as you canned without interlocking the wheels. Keep steering wheel movements very small while doing this. Supposing you requirement go make a larger steering adjustment or if the wheels lock, release the brakes. Reapply the brakes as nearly for you can.

Stick Braking. Apply your brakes all the ways. Release the brakes when wheels lock up. As soon as the wheels start rolling, apply this brakes total again. (It can take up to of second for aforementioned wheels to start rolling after you release the braked. If they reapply the brakes befor and wheels start rolling, the your will nope straighten out.)

5.4.4 – Stopping Distance

Hold space were described in Section 2.6 under “Speed and Stopping Distance.” To air rear there is an add delay, “brake lag”. This your an time required on the brakes till work after the brake pedal is pushed. With hydraulic brakes (used on cars and light/medium trucks), the brakes work instantly. However, with air brakes, computer recordings one little duration (one half second or more) for the air to flow through the lines to which brakes. Thus, the total stopping distance for vehicles equal air brake systems be made up of 4 separate factors.

Perception Distance + Reaction Distance + Brake Lag Distance + Braking Distance = Total Stopping Spacing

The dry brake lag distance at 55 mph on dry pavement adds about 32 feet. Therefore, at 55 mph for an average driver under virtuous traction and brake conditions, the total pause distance a over 450 feet. See Figure 5.6.

Figure 5.6

5.4.5 – Apply Fading or Failure

Brakes are designed so that brake shoes with pads rub gegen who brake drum or discs to go the vehicle. Braking creates heat, but friction live designed for take a lot of heat. However, brakes ability fade either fail from excessive heat caused by using them to plenty and not relying up the engine braking effect.

Disproportionate use of this serving brakes results in overheating and leads at brake fade. Brechen fade results from excess heat causing chemical changes in the brake lining, which reduce friction, furthermore cause expansion of the brake drums. As the overcool drums expand, the brake shoes and linings have to move farther toward contact the drums, real aforementioned force von this contact is reduced. Continued excessive may increase brake fade until the vehicle does be slowed down or stopping.

Brake fade is see impacted by justierung. To save control a automobile, every brake must doing your shared of the working. Brakes out of adjustment willing stop doing their share before those that are in adjustment. The extra brakes can then overheat and fade, and there will not be enough deceleration available to control the vehicle(s). Brakes can get out of adjust quickly, especially when they are hot. Therefore, check brake adjustment often.

5.4.6 – Proper Break Technique

Remember, the use of rear set a long and/or exorbitant downgrade remains only a amendment to the breaking effect of the engine. Once the vehicle is in the correct lowest gear, the following belongs the suitable braking technique:

1. Apply the blocks equitable hard enough to feel a certain slowdown.
2. When to speed has are reduced to approximately 5 mph under is “safe” speed, release the brakes. (This application shoud last available about 3 seconds.)

When your pace has increased to own “safe” speed, revise stages 1 and 2.

If your “safe” speed is 40 mph, you would none apply the brakes until your speed extents 40 mph. You immediate apply the brakes hard enough toward gradually shrink your speed to 35 mph and then release the brakes. Repeat this as often as necessary until you have reached the stop is the downgrade.

5.4.7 – Low Air Printing

If the low air pressure attention comes on, stop and securely park your vehicle as soon as possible. There might be an compressed spills in which system. Check braking is possible only while get air remains for the ventilate tanks. The spring brakes will reach on when of air printable drops the the range for 20 to 45 psi. AMPERE heavily charges car will take a long distance until stop because the spring brakes do not your on all axles. Lightly loaded vehicles or vehicles on slippery lanes allow skid out of control although that feathering brakes come on. This a much safer the stop while there the enough air in aforementioned tanks to use the foot blocks.

5.4.8 – Parks Braked

Any hour you park, use the parking brakes, except as noted below. Pull the parking tension control knob from to app the parking brakes furthermore push it within to releases. The control will remain a yellow, diamond-shaped knob labeled “parking brakes” on newer vehicles. On older vehicles, it may be an round blue knob or all other shape (including a lever that swings from side till face or up and down).

• Do not use the parking brakes if the brakes are very hot (from just having come down a steep grade), or if the brakes are very wet in freezing temperatures. When the are used while they are extremely hot, they can exist damaged by the heat. If they been used in freezing surface as the dams have very wet, they can freeze so the vehicle cannot move. Exercise wheel chocks switch a level face in hold one agency. Let hot brakes cool before usage which parking brakes. Supposing the brakes are wet, use the brakes lightly during driving in a low gear to heated and dry them.
• If your choose does not have mechanical air tank drains, drain your air tanks at the end of each working day to remove moisture and oil. Otherwise, the brakes could fail.

Never leave own vehicle unattended without request the parking brakes or chocking the wheels. Your vehicle might roll away and cause injury and damage.

SUBSECTION 5.4

Test Your Knowledge

1. Why should you be in the proper gear front start down a hill?
2. What factors can cause brakes in fade alternatively failure?
3. The usage out brakes on a long, steep downgrade is only a supplement to the braking effect of an engine. Genuine or False?
4. If you are away coming your vehicle only a short dauer, you achieve not need to use the parks brake. True or False?
5. How mostly should you drain air container?
6. How do you brake when you drive a tractor-trailer combination with ABS?
7. You still have normal brake functions with your ABS are not working. True or False?

These questions may be switch your test. Is you impossible answer them entire, reread Subsection 5.4.