Features
Hydraulic PowerShift (hot-shift) operation for 10-bolt automatic transmissions including Allison and Caterpillar
Ductile iron bearing cap, 117% stronger than gray iron, with 80% thicker steel clutch-pack discs
O-ring sealing configuration between housing and bearing cap reduces vibrational effects and improves clamp load
Nine speed ratios covering both low and high speed ranges
Wet Spline Lubrication option delivers 7 to 10 times greater output shaft life
SmartStart shock-load reduction and Electronic Overspeed Control (EOC) for driven-equipment protection
Tech Specs
- Mounting Type: 10-Bolt
- Shift Type: Hydraulic PowerShift (Hot-Shift)
- Compatible Transmissions: Allison and Caterpillar automatics
- Continuous Operation: Yes
- Series Continuous Torque Rating: 390 lb-ft (529 Nm) - verify actual rating on application pages
- Output Power (series): 56+ HP / 51+ kW
- Speed Ratios: Nine, including low and high speeds
- Lubricant Options: Pressure Lube or Wet Spline
- Output Types: SAE B Pump Flange, SAE C Pump Flange, ISO 7652 Pump Flange, Driveline
Additional Information

The Chelsea 281 Series is suited for demanding markets including fire and rescue, truck cranes, pumper/cleaner, and refuse vehicles. Rotatable cast-iron flanges reduce interference clearance issues, and the Positive Stop feature on driveline outputs eliminates oil seal damage from coupling contact. The hose is included with the assembly. Applicable Parker Chelsea reference documents include the 281/288 Series Parts List (HY25-2281-M1/US) and the 267/281/288/871/878 Series Owner's Manual.
Parts Manual: Chelsea 281 Series PTO Parts Manual (PDF) — exploded views, item numbers and the full parts breakdown for this series.
