MACK 20QE3218M4 Trailer Brake Valve Johnny Bar

( Manufacturer Part Number: 20QE3218M4 ), ( Type: Trailer Brake Valve / Johnny Bar ), ( Country Of Origin: United States )

Review MACK Trailer Brake Valve Johnny Bar Tag#

Introducing the Mack 20QE3218M4 Johnny Bar Trailer Brake Valve, a high-performance component designed to ensure optimal braking performance for your trailer. This valve is an essential upgrade for any heavy-duty towing application, providing reliable and consistent braking power.

The Mack 20QE3218M4 Johnny Bar Trailer Brake Valve is a four-way, pneumatic valve, meaning it can apply and release both the trailer brakes and the parking brakes, as well as control the service brakes on the trailer. The valve body is made from durable cast iron, ensuring a long service life and withstanding the rigors of heavy-duty towing.

One of the most notable features of this valve is its Johnny Bar design. The Johnny Bar, located on the valve spool, helps prevent the accidental application of the trailer brakes when the service brakes on the towing vehicle are applied. This feature is particularly useful when maneuvering in tight spaces or making sharp turns, as it prevents the trailer from swinging or fishtailing, thus improving safety and control.

The Mack 20QE3218M4 Johnny Bar Trailer Brake Valve is also designed with ease of maintenance in mind. The valve comes equipped with accessible grease fittings, allowing for regular greasing to ensure smooth operation and prolong the life of the valve. The valve also features a built-in bleeder screw, making it simple to bleed the air system should the need arise.

The Mack 20QE3218M4 Johnny Bar Trailer Brake Valve is compatible with a wide range of trailer brake systems and can be easily installed in place of standard trailer brake valves. Its compact design and rugged construction make it an excellent choice for heavy-duty towing applications, providing reliable and consistent braking power to ensure a safe and secure towing experience.

Pros and Cons of Buying a Mack 20QE3218M4 Trailer Brake Valve (Johnny Bar)

The Mack 20QE3218M4 Trailer Brake Valve, also known as the Johnny Bar, is a crucial component in a trailer brake system. It allows the driver to control the trailer brakes separately from the tractor unit. In this article, we will discuss the advantages and disadvantages of purchasing this specific trailer brake valve.

1. Durability: The Mack 20QE3218M4 is known for its robust construction. It is built to withstand harsh conditions, making it an excellent investment for commercial use.

2. Easy to Install: This trailer brake valve is relatively easy to install. It can be mounted on the tongue of the trailer and connected to the air supply line.

3. Control: The Johnny Bar provides the driver with the ability to apply and release the trailer brakes independently of the tractor brakes. This feature is essential for safe and efficient towing.

4. Adjustable: The Mack 20QE3218M4 comes with an adjustable feature that allows the driver to fine-tune the brake application for different trailers or loading conditions.

1. Cost: Compared to other trailer brake valves in the market, the Mack 20QE3218M4 is relatively expensive.

2. Maintenance: Like any other mechanical component, the Johnny Bar requires regular maintenance to ensure its proper functioning. This includes checking the air supply line, adjusting the valve, and lubricating the moving parts.

3. Complexity: While the Mack 20QE3218M4 is not overly complicated, it does have several parts that need to be assembled correctly for optimal performance.

The Mack 20QE3218M4 Trailer Brake Valve, or Johnny Bar, offers several advantages, including durability, easy installation, control, and adjustability. However, it also comes with some disadvantages, such as cost, maintenance requirements, and complexity. Ultimately, the decision to purchase this specific trailer brake valve depends on the user's individual needs, budget, and towing requirements.

If you require a heavy-duty trailer brake valve for commercial use, the Mack 20QE3218M4 is an excellent investment. Its robust construction, ease of installation, and control features make it a worthwhile investment for safe and efficient towing. However, if you are on a tight budget, there are other less expensive options available in the market that may suit your needs better. It is essential to consider all factors before making a purchase decision.

Details:

GOOD USED, DIRTY SCRATCHED, DINGED OR DENTED MACK TRAILER BRAKE VALVE 20QE3218M4, JOHNNY BAR.

part #: 20qe3218m4 prices

• $48.50-$59.99

specifications dashparinterio:

• for makes: Mack
• mpn: 20qe3218m4
• type: Trailer Brake Valve / Johnny Bar
• country of origin: United States

general dashparinterio:

• Commercial Truck Parts > Interior > Interior Controls
• condition: Used

shipping dashparinterio:

• service: USPS Ground Advantage
• transit: 5-10 Days
• class: Standard
• type: Calculated
• cost: $8.87
• carrier: USPS

payments dashparinterio:

• other
• wallet: Paypal
• credit card: Diners-club

seller dashparinterio:

• # reviews: 100
• rating: 98.9%
• city: Ford, Washington

offer dashparinterio:

• quantity: 1
• availability: In Stock
• sold: 0
• started: February 14, 2026
• options: Ship-to-home

returns dashparinterio:

• policy: No Returns

Mack 20QE3218M4 Is Similar To:

• Fueled To Create Ct-1000 Peterbilt Kenworth Freightliner Air Brake Knobs Chrome Metal Mack Screw On Truck (21% similar) Installation requires 8-32 Allen key is included with pair purchase. Epoxy topped metal emblem. Longer that standard air valves to allow for easier pulling. Fit most semi trucks with screw on air valves common thread is 5/8 for styles in. Potability ken worth freighting air brake knobs chrome metal ...(March 4th, 2025)