899 Series

The Chelsea 899 Series Power Take-Off (PTO) is a constant mesh (non-shiftable) PTO designed for Allison 4700 transmissions, delivering industry-leading performance with torque capacity up to 670 lb-ft. Engineered for tight chassis packaging, it improves clearance by fitting between the transmission and frame rail while routing the pump output toward the rear of the transmission for optimal space utilization. Designed as a fully integrated unit rather than an extension-style PTO, the 899 Series features a one-piece main shaft that eliminates intermediate input splines between the PTO and output section. This improves strength, reduces wear points, and enhances long-term durability in demanding applications. A rear-mounted support bracket allows the assembly to mount securely while keeping the housing and gear section tightly positioned against the transmission for improved clearance. The pump interface is located at the rear of the transmission, supporting a compact installation layout, while Wet Spline Technology helps extend PTO and pump shaft life under continuous-duty and high-load conditions. The 899 Series is available for transmissions with or without coolers, retarders, or both, offering broad installation flexibility. The Chelsea 899 Series PTO is commonly used in aerial equipment, fire and rescue vehicles, snow and ice service trucks, defense applications, and other mobile equipment where maximum torque output and space-efficient installation are required.