Description
ARB Air Locker differential (part number RD128) is a pneumatically activated locking differential for the Rover Type banjo axle, 24-spline, 1.24-inch shaft diameter, with a 3.54 gear ratio, available for both front and rear positions, fitting the Land Rover Defender 90 (1994–1995, 1997), Defender 110 (1993), Discovery (1993–2004), and Range Rover (1993–1995). NOTE: Suits the shimmed type third member (not the early adjuster nut type) which can be visually identified by the Dana logo cast into the third member between the two finds of the right hand side.
The ARB Air Locker is a pneumatically operated locking differential that replaces the open differential carrier in the vehicle’s axle. When locked, it forces both axle shafts to rotate at the same speed as the ring gear, delivering equal torque to both wheels simultaneously regardless of traction conditions. When deactivated, the unit returns to fully open differential behavior with no effect on normal on-road driving dynamics or driveline wear.
The locking mechanism is pneumatically actuated via an air line connected to an onboard compressor (sold separately). A solenoid valve controls air delivery to the differential, and a cab-mounted switch allows the driver to engage or disengage the locker without leaving the driver’s seat. ARB’s patented timed locking mechanism is engineered for high-strength engagement and ultra-fast unlocking response.
The Air Locker features a two-piece steel construction with minimal internal moving parts to maximize reliability under sustained off-road use. The annular seal is steel-reinforced and elastomer-bonded, rated for extreme climatic temperature ranges. ARB backs this unit with a 5-year warranty.
- Fitment: Rover Type banjo axle, 24-spline, 1.24-inch shaft, 3.54 ratio — front or rear position — fits Land Rover Defender 90 (1994–1995, 1997), Defender 110 (1993), Discovery (1993–2004), and Range Rover (1993–1995). Suits the shimmed type only (not the early adjuster nut type); can be visually identified by the Dana logo cast into the differential assembly between the two fins on the right-hand side.
- Provides 100% traction on demand without affecting on-road drivability or driveline wear
- Pneumatically activated — requires an onboard air compressor for operation (sold separately)
- Patented timed locking mechanism delivers high-strength engagement and ultra-fast unlocking
- Steel-reinforced, elastomer-bonded annular seal rated for extreme climatic temperatures
- Two-piece steel construction with minimal moving parts for maximum reliability
- Driver-operated from the cab via included activation switch and solenoid valve assembly
- Kit includes: Air Locker differential, activation switch, solenoid valve, air line, and bulkhead fitting
- Warranty: 5 years
- Sold individually
Specifications
| Part Number | RD128 |
| Brand | ARB |
| Color | Silver |
| Material | Steel |
| Axle Type | Rover Type (Banjo) |
| Spline Count | 24 |
| Shaft Diameter | 1.24 in |
| Gear Ratio | 3.54 |
| Position | Front or Rear |
| Activation | Pneumatic (air compressor required, sold separately) |
| Kit Contents | Air Locker differential, activation switch, solenoid valve, air line, bulkhead fitting |
| Warranty | 5 Years |
Fitment Notes
The RD128 fits the Rover Type banjo axle with a 24-spline shaft and 3.54 gear ratio, covering the Land Rover Defender 90 (1994–1995, 1997), Defender 110 (1993), Discovery (1993–2004), and Range Rover (1993–1995). This unit suits the shimmed type only — not the early adjuster nut type — identifiable by the Dana logo cast into the differential assembly between the two fins on the right-hand side.
Important: This listing is for the RD128, which fits the standard Rover Type banjo axle at a 3.54 ratio with a 24-spline shaft. If your application uses a 10-spline shaft, see ARB part number RD127. If your vehicle uses a Range Rover P38A-type axle, see ARB part number RD138. For vehicles with a Salisbury-type rear axle, see ARB part number RD161.