You really need to learn part 5: Air brake system before reading this. The braking system has parts to control the trailer brakes, in addition to the parts described in Section 5 in combination vehicles. These components are described below.
6.2.1 вЂ“ Trailer Hand Valve
The trailer hand valve (also referred to as the trolley valve or Johnson club) works the trailer brake system. The trailer hand valve ought to be utilized simply to test the trailer brake system. Don’t use it in driving due to the risk of making the trailer skid. The base braking system delivers atmosphere to all or any of this brakes regarding the automobile (such as the trailer[s]). There was significantly less risk of causing a jackknife or skid when working with simply the base braking system.
Never ever utilize the hand valve for parking because all of the atmosphere might leak away unlocking the brake system (in trailers that do not have springtime brake system). Always utilize the parking brake system whenever parking. In the event that trailer doesn’t have springtime brake system, usage wheel chocks to help keep the trailer from going.
6.2.2 вЂ“ Tractor Protection Valve
The tractor security valve keeps atmosphere into the tractor or vehicle brake system if the trailer break away or establish bad drip. TheвЂњtrailer controls the tractor protection valve atmosphere supplyвЂќ control valve into the cab. The control valve lets you start and shut the tractor security valve. The tractor security valve shall shut immediately if air stress is low (when you look at the variety of 20 to 45 psi). If the tractor security valve closes, it prevents any fresh atmosphere from losing sight of the tractor. It allows the atmosphere from the trailer crisis line. This leads to the trailer crisis brake system in the future on, with feasible lack of control. (crisis brakes are covered subsequent.)
6.2.3 вЂ“ Trailer Air Supply Control
The trailer atmosphere supply control on more recent automobiles is just a red eight-sided knob, that you used to get a handle on the tractor security valve. You push it in to produce the trailer with air, and pull it away to shut the air off and put the trailer emergency brakes on. The valve will thus pop out shutting the tractor security valve) as soon as the atmosphere force falls in to the variety of 20 to 45 psi. Tractor security valve controls or вЂњemergencyвЂќ valves on older automobiles may well not run immediately. There might be a lever in place of a knob. The position that isвЂњnormal employed for pulling a trailer. The вЂњemergencyвЂќ position is employed to shut the air off and put from the trailer crisis brake system.
6.2.4 вЂ“ Trailer Air Lines
Every combination automobile has two atmosphere lines, the solution line as well as the crisis line. They operate between each car (tractor to trailer, trailer to dolly, dolly to 2nd trailer, etc.)
Provider Air Line. The solution line (also known as the control line or line that is signal holds atmosphere, which can be managed because of the base braking system or kasidie perhaps the trailer hand braking system. Based on just exactly just how difficult you click the base braking system or hand valve, the stress within the solution line will change similarly. The solution line is linked to relay valves. These valves let the trailer brake system to be employed more quickly than would otherwise be feasible.
Crisis Air Line. The crisis line (also known as the supply line) has two purposes. First, it provides atmosphere into the trailer atmosphere tanks. 2nd, the crisis line controls the crisis brake system on combination vehicles. Loss in atmosphere force into the crisis line causes the trailer emergency brake system in the future on. A trailer could cause the pressure loss breaking loose, therefore tearing apart the emergency atmosphere hose. Or it may be due to a hose, tubed metal, or other part breaking, permitting the fresh air out. As soon as the crisis line loses force, it causes the tractor security valve to shut (the atmosphere supply knob will pop away).
Crisis lines in many cases are coded aided by the color red (red hose, red couplers, or other components) to help keep from getting them confused because of the service line that is blue.