Trailer hand brake valve. Leaks at exhaust port wh When air pressure is below 40 PSI. The trolley valve should only be used when testing the tailor brakes, and should never be used while driving. The trailer supply valve is usually a push/pull type valve near the driver that supplies air to the trailer's brake system through the supply line. Freightliner Trolley / Trailer Brake Hand Valve 170. All of the above, if you start a Study with Quizlet and memorize flashcards containing terms like Why should you not use the trailer hand service brake/valve while driving?, What does the trailer air supply control do?, What does the Blue Service Line do? and more. 265031 Automann The driver can use the hand valve to apply the trailer brakes. Conclusion Proper maintenance and troubleshooting of trailer air brakes are crucial for ensuring the safety and performance of your vehicle. Trailer Hand Valve: The trailer hand valve controls airflow from the tractor to the trailer’s service air brake system without applying the tractor brakes. " and this is from another section under Prevent Trailer Skids " (if trailer wheels lock up) Release the brakes to get traction back. Check out the deal on Haldex KN20541 In-Column Mount Trailer Brake Hand Valve at AnythingTruck. You should feel the brakes come on. Oct 28, 2019 · 1 Pair Service Emergency Gladhands with Valve Switch, Die Cast Aluminum Glad Hands with Valve Switch, Universal Air Hose Brake Coupling Connector Handshake Kit with Valve Switch, for Truck Semi Trailer Tractor RVs · Material: high quality aluminum · Port Size: 3/8'' FPT, 3/4'' MPT or 1/2'' FPT (The connector at the port can be removed as May 29, 2017 · The air is leaking from the blue service line gland hands and exhaust port on the firewall when I press the foot brake or pull the trailer brake hand valve, the red valve is out, not connected to a trailer, yellow valve can be pressed in or it can be out, air will still Leake from the gladhand and firewall. bl>- Traller Hand Control Valve t when only foot valve is applied. Adherence to these instructions will ensure a sound, leak-free installation of the valve. Apr 23, 2024 · What is the first thing you should do to prevent a trailer skid? Step on the brakes hard several times to stop the skid Use the trailer hand brake Recognize that a skid has started to occur in the mirrors Maintain a constant speed to adjust the truck and trailer in a smooth fashion Nov 25, 2023 · The trailer hand valve, meant for operating the trailer brakes, should not be used while driving due to the risk of the trailer skidding. Get high-quality trailer hand brake valve from Alibaba. TC-2 Style Trailer Hand Brake Valve Replaces Bendix 276270-1/4 SUPPLY, DELIVERY AND EXHAUST Haldex hand operated trailer brake control valve. in a typical FMVSS 121 compliant tractor-trailer when you actuate the trailer hand control valve which circuit supplies air to the trailer service brakes when the system is functioning normally A. Your truck should have a PP-1 style dash valve in order to use this kit. Do not use the trailer hand brake to straighten out the rig" Aug 30, 2017 · Buy TRAILER HAND CONTROL BRAKE VALVE - REPLACES KN20541 476356C92: Hydraulic Parts - Amazon. 31” – Depth 2. It should be used only to test the brakes. Air is sent to all of the vehicle’s brakes, including the trailers, by the foot brake. Explore Bendix Marketing Center for resources, tools, and information to enhance your understanding of Bendix products and vehicle safety solutions. The most common vehicle application is the independent control of the trailer’s service brakes on a tractor trailer combination. This causes the gradual actuation of the hand-lever to either feed air pressure in or release air pressure out of the Tristop-cylinder or the spring brake cylinder correspondingly. This allows for precise control of the trailer, particularly during low-speed maneuvers, parking, and certain emergency situations where selective braking is critical. The trailer hand valve (also called the "trolley valve" or "Johnson bar") works the trailer brakes. Never use the trailer hand valve while parking because doing so may release the air pressure from the braking system, releasing the brakes that are holding the vehicle in place. See full list on trucksauthority. Sep 22, 2019 · Trailer hand brake valve installation diagram needed Discussion in ' Ask An Owner Operator ' started by crucar1800, Sep 22, 2019. Jan 15, 2017 · The trailer hand valve applies the trailer service brakes independently of the truck. If the foot valve application is of a higher pressure than that of the hand valve, the two-way check valve will shift to the lower pressure side, allowing the higher pressure to be directed to the tractor and trailer brakes. com for 2-, 3-, and 4-wheelers. Vents air pressure from a false charged system when the lead trailer supply shut-off valve is mistakenly closed. 5002 sales@eaglemark4. The most common use of the trailer control valve is for independent control of trailer service brakes, however, the valve can be used for any application where graduated application pressure is required. The trailer hand valve, also called the trolley valve or Johnson bar, works the trailer brakes. Good morning! I am doing the HRTP and am having a heck of time separating out the difference between the tractor protection valve, trailer hand valve, parking b - Page 1. The hand valve sets the initial braking pressure for the trailer during road tests and brake adjustments. It should only be used for testing, adjusting, or parking the trailer. If it does it with different trailers and you’ve already replaced stuff. Any time a trailer brake application is made by use of the hand valve, the driver may depress the foot valve treadle. You can tell if you have a PP-1 dash valve by the large chrome nut that holds it in the dash and the pin that holds the button onto the shaft. Technician A says that the steering column mounted, hand control valve actuates the tractor service brakes without applying the trailer brakes. Describe what the trailer air supply control does? The tractor air supply control on newer vehicles is a eight-sided knob, which you use to control the tractor protection valve. com Mar 31, 2025 · The KN20541 Hand Operated Valve is a robust, in-column mount trailer brake control valve designed for precise air brake operation, seamless OEM replacement, and reliable performance in heavy-duty trucks and trailers. A Bad Air Brake Relay Valve The work of the air brake relay valve is to remotely control the brakes at the rear of a semi-trailer in a tractor-trailer combination or a heavy truck. c) Both of these statements are true, Trailer Hand Valve and more. I always test the hand valve , to see what it takes, for the trailer brakes to grab. You must have an Endorsement A specified on your licence to operate a vehicle equipped with an air brake system. Test trailer service brakes: Check for normal air pressure, release the parking brakes, move the vehicle forward slowly, and apply trailer brakes with the hand control (trolley valve), if so equipped. You need a ~ Foot Valve Leaks at exhaust wilh all brakes released. com FREE DELIVERY possible on eligible purchases The trailer hand valve (also called the “trolley valve” or “Johnson bar”) works the trailer brakes. Use this kit to add the ability to pull an air brake trailer to a dump truck This kit is meant for trucks with an existing PP-1 style dash valve Includes a trailer dash valve, tractor protection valve, inline quick release valves, swing-away gladhands, nylon air tubing, push-to-connect fittings, zip ties, instructions, and tech support Sep 26, 2022 · The hand valve works with an air system that controls the brakes and movement of the trailer. The hand valve, or "spike" (Fig. Check that the foot valve is releasing air between it and the trailer hand brake valve. The endorsement is not required when operating a Class 3 or 5 vehicle licensed as a farm truck or trucks with air over hydraulic brakes. Technician B says that the hand control valves sources its air from the tractor secondary circuit. This line is crucial and connected to relay valves for proper brake function. The trailer hand valve should be used only to test the trailer brakes. TRAILERS ** The air brake system of a trailer is entirely dependent upon the air brake system of the towing vehicle for its air supply and control. The three basic components of the TC‐7 valve are available separately (valve, handle, bracket) to accommodate National Sales & Service PO Box 946 Mansfield, OH 44901 Phone: 800. I already have the Maxbrake installed and it works fine but, like Roger's, mine is mounted under the dash by my left knee. It is very important to operate this valve only while the truck is moving, as if the hand valve were turned, the trailer could slide. In normal braking, pressing the brake pedal pressurizes the service line. Mar 3, 2021 · If it’s the same trailer all the time I would check the regulator valve connected to the reserve tank under it. The relay valve that sends air pressure from the trailer air tank to the trailer brake chambers d. The reservoir (s) are filled at the same time or after the spring brakes have been released dependent Aug 29, 2022 · Adding trailer air brakes when converting a straight truck We've created this kit for people with an air brake straight truck that needs to be converted to a tractor. If you use the trailer hand brake while driving, you can cause the tailor to skid. Study with Quizlet and memorize flashcards containing terms like Why should you not use the trailer hand valve while driving?, Describe what the trailer air supply control does. The foot brake sends air to all the brakes on the vehicle (including the trailer (s). 99 * High Quality Brake Valve * For Trailer Break * With Handle * Sold Individually * Warranty On Brake Valve Against Defects In Workmanship & Material From Date Of Purchase * Replaces OE Number: K024943 ***This Is An OEM Replacement Part/Not Aftermarket*** Steering Column Mounted Hand Operated Trailer Brake Control Valve with Handle 0 Rating $79. 39) is added so that you can apply the trailer’s brakes independent of the tractor. Get deals on automotive parts, truck parts and more. com Jun 5, 2012 · Buy Tractor Trailer Hand Brake Valve Bendix Style 229635: Proportioning Valves - Amazon. Depending on how hard you press the foot brake or hand valve, the pressure in the ser ce line will similarly change. The Power Products Control Valve is the perfect solution for ensuring effective braking and safe operation of your trailer. 1 – Trailer Hand Valve The trailer hand valve (also called the trolley valve or Johnson bar) works the trailer brakes. Which of these statements is true? a) The trailer hand valve should be used only to test the trailer brakes b) The foot brake sends air to all the brakes on the vehicles (including the trailer (s)). Trailer Control Valve with a material number 9730090020 is available. Using it while driving could create a skid. By regularly inspecting and servicing the various components, such as the air compressor, air valves, brake chambers, and brake shoes, you can prevent potential failures and costly repairs. All Rights Reserved. Study with Quizlet and memorize flashcards containing terms like to stop a trailer skid you should a) Counter steer b) Use the trailer hand brakes c) Release the service brakes, Tractor protection valve will close and the trailer emergency brakes will come on when there is a major leak in the ___ brake line. The TC-7™ trailer control brake valve is a hand operated control valve that provides graduated control of service brake air pressure. The service air line is controlled by both the foot brake and the trailer hand valve. Check out the deal on Bendix TCS-9000 Trailer Hand Brake Control Valve Retrofit Kit, Self-Returning Handle at AnythingTruck. Ideal for commercial trucks, this valve is crafted from Engineering Grade Composite (EGC) for a one-piece housing that guarantees both durability and resistance to Using the trailer hand valve while driving can cause the trailer wheels to skid. When air pressure is introduced it begins to fill the spring brake chambers through the delivery ports. Braking of the trailer com-mences by the pressure increasing in the connecting ‘supply’ hose. Hand valves are the fluid equivalent of an electrical switch, and their use is often required when trucks have attached tractors. , Describe what the service line is for and more. Back then, that was his theory. Interested in another ? See more on new Inform. But when it comes to product performance and support, Bendix valves have set the standard for everyone else. Clear as mud. A trip through technology: Tasks of the hand-brake in the emergency and parking brake system Hand-brake valves are used for actuating the emergency and the parking brake system. This test is best performed while hooked to a trailer. Explanation The trailer hand valve, also called the trolley valve or Johnson bar, is used to work the trailer brakes. It ensures that the trailer brakes engage and disengage at the same time as the towing vehicle's brakes, promoting stability and control during braking. Apr 16, 2025 · The trailer hand valve (also called the trolley valve or Johnson bar) works the trailer brakes. The foot brake sends air to all of the brakes on the vehicle (including the trailer(s)). Apr 1, 2024 · The paper presents an overview of the basic air brake valves used in agricultural trailers and a conceptual solution proposed by the authors. Eventually the pressure builds until it cages (retracts) the spring allowing the trailer to move. control of service brake air pressure. L31225 This document details the recommended assembly and installation instructions for Haldex Trailer Brake Control (TBC) Valves. Do not use it in driving because of the danger of making the trailer skid. Using the foot brake sends air to all brakes on the vehicle, including the trailer (s). com FREE DELIVERY possible on eligible purchases Sep 13, 2015 · Have heard of it as trolley, Johnson Bar, trailer hand brake valve. a) Parking b) Service c) Emergency, If you must back your trailer on a curved path Discover Bendix Marketing Center for tools, resources, and information on Bendix products and services. It may also result in trailer breakaway situations and disconnection of the emergency brake line. Air trailers have red or blue tires and are connected to the truck with glad hands. Using it while a vehicle is in motion could cause a skid. The most common application is the control of trailer brakes independent of tractor brakes; however, the valve may be remotely operated type valve is connected to the operating handle by a linkage rod. The air pressure helps the driver control the movement of the trailer, which can be difficult on slick roads. 85 USD Not Yet Rated A hand valve on a truck is a control for air pressure that goes to the brakes and the trailer. When making an emergency stop, use both valves to apply maximum braking pressure. ake or the trailer hand brake. Operating this valve should only be done to test trailer brakes and not while driving to prevent skidding. 6. 28” Approximate Weight: 2. Handle applies 70° maximum. 99 SKU: BAP276270 Check for normal air pressure, release the parking & emergency brakes, move the vehicle forward slowly, and apply trailer brake with the trailer hand valve, if so equippeD) This best describes: Dec 12, 2024 · The trailer hand valve, often referred to as the “trailer air supply valve” or “trailer brake valve,” is used to manually control the brakes on a trailer. The trailer hand valve is only used to put the trailer brakes to the test. Hand Brake Trailer Brake Hand Valves Categories 12V ABS Systems (TCSII & iABS) 12V Roll Stability Systems (RSSplus) Check out the deal on Bendix TCS-9000 Trailer Hand Brake Control Valve Retrofit Kit, Positioning Handle at AnythingTruck. e applied and foot valve released. Its primary function is to provide the driver with manual control over the trailer brakes, independent of the foot brake (service brake) and the spring brakes. In-line quick release valve 401145 mounts between tractor protection valve and air lines. This activates a valve in the trailer which directs air from the reservoir and the emergency line to the brake cylinders where it moves the piston that activates the brakes. com Our product range covers all the demands of a conventional braking system, including foot brake valves, hand brake valves, relay valves, brake pressure regulators, trailer control valves, air suspension valves and selector valves for operating with containers – also as a perfect addition to the electronic control system. Learn how trailer brake components work, why they're important, and how to maintain them for safety. vehicle. 837. Firs! no brakes, then on all at once. supply circuit D. In combination vehicles the braking system has parts to control the trailer brakes, in addition to the parts described in Section 5. There is much less danger of causing a skid or jackknife when Apply and release the trailer control valve and note that only the trailer brakes apply and release. Hand Brake Valve, Parking + add. Steering Column Mounted Hand Operated Trailer Brake Control Valve with Handle Control Valves $79. Aug 13, 2025 · The trailer hand valve, also known as the “trolley valve” or “Johnson bar,” is primarily used to independently apply the trailer brakes without engaging the tractor brakes. Sep 30, 2019 · This edition of Bendix Tech Tips Series addresses regulations for dash valve trip pressures and how fleets and owner-operators stay compliant and safe. The output from the trailer brake lever then goes to a two-way check valve (26) and then feeds to another two-way check valve (26) that may or may not be part of the tractor protection valve (24). The trailer What is a trolley valve? The trolley valve, or trailer hand valve or Johnson bar, operates the trailer brakes on a combination vehicle. Special Notes none Product Description Manufacturer: Bendix Part Number: 102394N TC-7 Trailer Hand Brake Control Valve Ports: 1/4" NPT Final delivery Pressure: Full Reservoir Pressure Basic Valve 0nly, Handle and mounting bracket sold separately Self-Returning, Returns to 0 psi when the handle is released Cross References: 102394, 102394N, 060-102394N, 102959, 104099, 104599, 106129, 107258 Haldex KN20541 In-Column Mount Trailer Brake Hand Valve Part# 070-KN20541 Details / Buy $113. valve with a material number 9617251000 is available. Trailer brakes will B2Bendix B2Bendix Sep 1, 2025 · Steering Column Mounted Hand Operated Trailer Brake Control Valve with Handle Chrome and Parts (2451) 99. Mar 1, 2015 · The air brake hand valve applies and releases the semi-trailer service brakes. Learn about the trailer hand valve, tractor parking valve, and trailer air supply control. The two double check valves in the Bendix® TP-5TM valve, as seen in schematic view Figure 2, serve to pick up the highest pressure service signal from either the tractor front brake circuit, rear brake circuit or TC valve signal, operating the trailer brakes accordingly. Therefore, the air air brake system of the towing vehicle must be in good condition; otherwise it will be impossible to obtain a good brake performance on the trailer. The trailer hand valve (also called the trolley valve or Johnson bar) works the trailer brakes. Check for normal air pressure, release the parking & emergency brakes, move the vehicle forward slowly, and apply trailer brake with the trailer hand valve, if so equippeD) This best describes: Jul 14, 2011 · I ran Containers in the late 80`s to about 97, and the boss wanted us to stop, using the hand valve, to save on his tractor brakes. For safety, it is crucial to refrain from using this valve while in motion. Interested in another ABS Trailer Control Valve? See more on new Inform. Technician A says that the steering column mounted hand control valve actuated the tractor service brakes without applying the trailer brakes. The TC-2TM brake valve is a hand operated control valve which features a graduated control of air pressure. The most Valves direct the flow and release of air throughout an air brake systema big job for the network of compact components located on an 80,000-lb. 1/2 inch NPTM tractor port, 1/2 inch NPTF trailer port, 3-1/2 inches long. com Nov 28, 2016 · The trailer hand valve is used to apply the trailer service brakes independent of the towing vehicle’s brakes. When the pedal is let up, the service line pressure is decreased. Only use the trailer hand valve when you're parked for the reason of checking if trailer service brakes are functioning Describe what the trailer air supply control does? The trailer air supply control controls the tractor protection valve. The hand valve is typically supplied from primary and secondary circuits and plumbed to a two-way check valve (which is also fed from the foot valve). This device allows drivers to independently control the trailer brakes, providing an additional layer of control and safety in various driving situations. 2. Prevents the application of the lead trailer and dolly emergency brakes in the event of the loss of the rearward trailer. When the valve is depressed, the maximum amount of air flows through the service lines. Search the online platform for recommended trailer hand brake valve at competitive rates. At the same time, the pressure in the line leading from the hand brake valve (16) to the trailer control valve (17) is reduced. The three basic components of the TC‐7 valve are available separately (valve, handle, bracket) to accommodate The trailer brakes are controlled by the trailer hand valve (also known as the trolley valve or Johnson bar). In addit… Jun 14, 2024 · The service line in trucking carries air controlled by the foot brake or trailer hand brake, with pressure changing based on the brake application. Remanufactured TRAMEC Trailer Emergency Valve (TEV) - CoreFree For Direct Control of Trailer Spring Brakes Notes The logic of the TEV valve retains the ability of the driver to repeatedly apply and release the Parking/Emergency brakes, even with a damaged tank. The air pressure helps to prevent the trailer from moving out of control and causing an accident. Pull gently on the trailer with the tractor to check that the trailer emergency brakes are on. Mar 28, 2025 · Using the trailer hand valve while driving can activate emergency brakes, leading to loss of control and potential skidding. 41 lbs. 3% positive Shown is the brake system as a schematic layout or the actual routing in the vehicle on a 4x2 and a 6x4 vehicle or the brake system valves and tubing in separate circuits. Discover the parts of a combination vehicle braking system and how to use them safely. Understand air flows, tractor parking valves, trailer emergency brakes, and trailer service brakes. New Wabco Hand Brake Valve Part Number: 9617221840 Other OEM Part Numbers That Will Work: S9617221840, 2S9617221840, 2S961 722 184 0, 6300-9617221840, S9617221840, WAB9617221840, S961 722 184 0, S961-722-184-0 Combination Vehicle Air Brakes You should study Section 5: Air Brakes before reading this. May 7, 2009 · The trailer hand valve should be used only to test the trailer brakes. The hand valve is also known as the Johnson bar or trolley valve. com Check for normal air pressure, release the parking & emergency brakes, move the vehicle forward slowly, and apply trailer brake with the trailer hand valve, if so equipped. The trailer hand valve is used to apply the trailer service brakes independent of the towing vehicle's brakes. Study with Quizlet and memorize flashcards containing terms like The service air line controlled by: a. Do not use the trailer hand valve because of the danger of making the trailer skid. Apr 10, 2018 · What is the purpose of the Hand Valve Brake that's usually just to the right of the steering wheel? How does it work? Why is it used when coupling? Looking for the Bendix Hand Brake Valve 106131? Find it and many more Bendix parts at the lowest prices at Big Rig World! Mar 5, 2025 · The trolley hand valve, also known as the trailer hand valve or Johnson bar, is a crucial component in the air brake system of combination vehicles, particularly in tractor-trailers. Buy Air Brake Valves / Trailer Hand Control - New - H/D Truck - TWD 113730 online from NAPA Auto Parts Stores. The pressure applied to the line by the foot brake or the trailer hand valve b. Leaks t exhaust with foot brake appli Brakes not modulating properly. The trailer supply valve is usually a push/pull type valve near the driver that supplies air to the trailer’s brake system through the supply line. com FREE DELIVERY possible on eligible purchases Brake Pedal - Valve, Foot, M2, 2V, Trailer Hand Valve - Big Rig World carries Genuine OEM and Aftermarket parts to repair your vehicle at the lowest prices. External steering column mount. Technician B says that the hand control valve sources its air from the tractor secondary circuit when functioning normally. Mar 1, 2024 · About this item Premium OEM-Quality Replacement - The 800519 MV-3 air parking brake dash hand control valve is manufactured to meet rigorous industry standards, delivering performance and reliability that matches original equipment. These parts are described below. Aug 26, 2024 · A hand valve on a truck allows the driver to control the trailer brakes independently for added safety. Copyright © 2023 SEALCO. Dec 2, 2016 · On your pdf, the trailer brake lever (30) is attached in the red-secondary suppy line that also feeds the brake pedal valve (31). Part Number: 2522795C91 by International® - Part Type: Hand Control Trailer Valve - Condition: New - FREE DELIVERY on eligible purchases over $99. Delays the delivery of air to the rearward trailer until there is sufficient air in the lead trailer supply system. primary circuit B. Pull gently against them in a low gear to make sure the brakes work. The relay valve that connects the trailer air tanks to the trailer air brakes c. The most common vehicle application is the independent control of the trailer’s service br clamped to the exterior of the column. The service li Update your vehicle to be Ready for the Road Ahead™, with the Sealco 1/4" NPT Trailer Brake Hand Control Valve that pairs with a wide number of pneumatic operations. Explanation The trailer hand valve works the trailer brakes but should only be used when testing them. Before condemning the air brake system on a trailer, always be sure the air CDL program to check air brakes on combination vehicles. The most common application is the control of trailer brakes independent of tractor brakes; however, the valve may be used wherever a hand-controlled pressure graduation operation is needed. The trailer hand valve (also called the Trolley Valve or Johnson Bar) operates the trailer (s) brakes only and is entirely independent of the tractor brakes. Jun 9, 2023 · Braking Synchronization: The trailer control valve works in conjunction with the tractor's brake system to synchronize the braking action of the entire vehicle combination. Dimensions: Height 4. The harder you press the foot pedal (or pull the hand valve), the more braking force is applied. 1/4 inch NPT supply, delivery and exhaust ports. Because of the risk of making the trailer skid, it is not used in driving. This procedure will work for older “Pre-121” equipped trailers regardless of how many tanks and valves, or types of valves that you see. Always test the trailer brakes before driving with the hand valve or by pulling the air supply (tractor protection valve) control. It is responsible for directing the brakes on the trailer. secondary circuit C. Jul 8, 2025 · The trailer hand valve is, at its heart, a control valve strategically placed within the air brake system of a tractor-trailer combination. . Trailer control (TC) valves are hand operated, graduating control valves. All types of trailer air brake systems can be identified for troubleshooting purposes by starting from the brake chamber or spring brake assembly. 38” – Width 3. This site offers basic functionality without JavaScript, but do expect a degraded user experience. The trailer hand valve should only be used to test trailer brakes. The hand valve, as shown in Figure 2-7, is normally located on the steering column and its function is to apply the trailer brakes only, while the foot valve operates both the tractor and trailer brakes. With trailer control valve applied check exhaust port of foot brake valve for leakage with soap solution. Understand the essentials of a Trailer Brake Subsystem. So if you’re going down the road, you can pull the hand valve down and apply the trailer brakes independently of the truck. park/emergency circuit The trailer hand valve (also called the trolley valve or Johnson bar) works the trailer brakes. (See Weight Chart) * Only 5900L valve has locking handle. B2Bendix B2Bendix Check for normal air pressure, release the parking brakes, move the vehicle forward slowly, and apply trailer brakes with the hand control (trolley valve), if so equipped. Study with Quizlet and memorize flashcards containing terms like Why should you not use the trailer hand service brake/valve while driving? a) It applies all of the brakes evenly b) It could cause your service brakes to stop working c) It could cause a skid, What does the trailer air supply control do? a) Controls the trailer spring brakes b) All answer choices for this question c) Supplies Dec 31, 2020 · Buy MV-3 Compatible with Peterbilt Brake Dash Hand Valve 800523 065248 107753: Valves - Amazon. Also, where is the trailer hand valve located Operation The supply port on the valve is connected to an air line from the red gladhand. The friction applied by this valve slows and stops the brake drum’s turning, which eventually stops the wheel. vafdxue dmf rdcsr tsa utdxf eiwq wxd kkdmtrs rjtcgwih qle