Udor RBC 122K Reduction Gearbox — 22 HP Plunger Pump Drive

The Udor RBC 122K is the most popular reduction gearbox in the Udor range, purpose-built for coupling petrol or diesel engines to Udor plunger pumps. Its compact aluminium housing and 2.176:1 reduction ratio make it the go-to drive solution for mobile pressure washing, water blasting, and spray applications across New Zealand. Available in three variants to suit different engine shaft sizes and power requirements, the RBC 122 series covers builds from 22 HP right through to 31 HP.

Model Variants

Model	Code	Max Power	Engine Shaft
RBC 122K 1″	890010	22 HP (16.4 kW)	1″ (25.4 mm)
RBC 122K 1-1/8″	890009	22 HP (16.4 kW)	1-1/8″ (28.6 mm)
RBC 122X 1-1/8″	890008	31 HP (23.0 kW)	1-1/8″ (28.6 mm)

Specifications

Reduction Ratio	2.176 : 1
Pump Shaft	24 mm
Flange Standard	SAE J609B
Oil Type	SAE 85/140 gear oil
Oil Capacity	0.32 litres
Weight	~2.3 kg
Housing	Die-cast aluminium

Compatible Pump Series

The RBC 122 gearbox fits the following Udor plunger pump series:

• B Series — B, BS, BCW, BWT, BK
• C Series — C, CH, CS, CWT, CK, CX

Select the correct variant based on your engine shaft diameter (1″ or 1-1/8″) and the maximum horsepower of your engine. The RBC 122X is required for engines above 22 HP.

Applications

• Mobile pressure washers and water blasters powered by petrol or diesel engines
• Truck-mounted and trailer-mounted wash systems
• Agricultural and horticultural spray rigs
• Vehicle and fleet wash equipment
• Building and house wash setups
• Industrial cleaning systems requiring engine-driven pump power

Key Features

• Most popular Udor plunger pump gearbox — proven reliability in thousands of units
• Lightweight die-cast aluminium housing for easy handling and reduced rig weight
• 2.176:1 reduction ratio optimises pump RPM for engine-drive applications
• SAE J609B standard flange ensures direct bolt-on compatibility with Udor B and C series pumps
• Low oil volume (0.32 L) — simple maintenance with standard SAE 85/140 gear oil
• Three shaft options cover the most common small engine configurations
• 31 HP rated variant (RBC 122X) available for higher-powered builds

Technical Documents

• Udor RBC 122 Gearbox Brochure (PDF)
• Udor RBC 122 Parts Schematic / Exploded View (PDF)
• All Udor Gearbox Documents

Parts & Service

AES Waterblasters is the sole New Zealand distributor for Udor products. We carry genuine RBC 122 gearbox assemblies, gasket kits, bearings, seals, and all internal components. Whether you need a complete gearbox or individual replacement parts, contact us on 09 271 4782 for pricing and availability.

Related Models

Other Udor reduction gearboxes:

• Udor RNK 122 — 40 HP Heavy-Duty Gearbox
• Udor RP 123 / SI 123 — 6 HP Compact Gearbox