AUTOMANN SR7 Spring Brake Modulator Valve Part No: 170.K021558

The 170.K021558 / SR7 Type Spring Brake Modulating Valve (Automann) is a precision valve used in heavy truck air brake systems to modulate spring brake engagement and release. It receives control and balance air signals to proportionally actuate the spring brake chamber, thereby improving driver control and braking smoothness. The valve features ½" NPT for supply, four 3/8" NPT delivery ports, 3/8" push-to-connect control and balance ports, and a ¼" NPT park control port. The mounting uses 3/8"-16 studs approx. 0.94" in length. It also meets compounding and FMVSS 121 requirements for safety. Automann’s version is manufactured to match Bendix SR-7 performance, enabling reliable replacement or retrofit. Wofford Truck Parts stocks it with support for installation, compatibility checks, and shipping reliability. In operation, it helps regulate the spring brake system smoothly, especially under varying pressures and load conditions, reducing wear and enhancing safety.