Udor RP 123 Reduction Gearbox

The Udor RP 123 is a compact reduction gearbox designed to couple petrol and diesel engines to Udor plunger pumps. With a 2.3:1 gear reduction ratio, the RP 123 converts typical small engine speeds of approximately 3,400 RPM down to the optimal pump operating speed of around 1,450 RPM, protecting pump internals and delivering consistent high-pressure performance. Rated for engines up to 6 HP (4.5 kW) with a standard 3/4-inch (19mm) keyed engine shaft, the RP 123 is the ideal drive solution for portable and trailer-mounted pressure washing systems across New Zealand.

Specifications

Part Number	216 RP 123
Udor USA Code	5055.E7
Type	Reduction Gearbox
Gear Ratio	2.3 : 1
Maximum Engine Power	6 HP (4.5 kW)
Engine Shaft	3/4″ (19.05 mm) keyed
Input Speed (Engine)	~3,400 RPM
Output Speed (Pump)	~1,450 RPM
Oil Type	SAE 85W/140 gear oil
Oil Capacity	0.22 L
Compatible Pump Series	Udor PN, PS, A, AK (AKC 09–11/25 S), AWT

Applications

• Portable petrol-powered pressure washers (up to 6 HP)
• Trailer-mounted high-pressure cleaning systems
• Engine-driven agricultural and horticultural spray rigs
• Mobile vehicle wash and fleet cleaning units
• Commercial and industrial site wash-down equipment
• Water blasting and surface preparation rigs

Key Features

• 2.3:1 reduction ratio converts engine speed (~3,400 RPM) to optimal pump speed (~1,450 RPM)
• Compact aluminium alloy housing for lightweight, corrosion-resistant operation
• Standard 3/4″ (19mm) keyed input shaft suits Honda GX, Briggs & Stratton, and other popular small engines
• Direct bolt-on mounting to compatible Udor PN, PS, A, AK, and AWT plunger pumps — no adapter plates required
• Hardened helical steel gears for smooth, quiet operation and extended service life
• Low oil volume (0.22 L of SAE 85W/140) simplifies maintenance
• Designed and manufactured by Udor S.p.A. in Rubiera, Italy

Technical Documents

• Udor RP Gearbox Product Brochure (PDF)
• Udor RP Gearbox Exploded Parts View (PDF)
• Udor RP Gearbox GA Drawing (PDF)
• All Udor RP Documents

Parts & Service

AES Waterblasters is the sole authorised Udor distributor in New Zealand. We carry genuine Udor RP 123 gearbox components including gear housings, bearings, seals, input shafts, and hardware. All parts are sourced directly from Udor Italy to ensure correct fit and reliable performance. Contact us on 09 271 4782 or email sales@waterblasters.co.nz for pricing, availability, and technical support.

Related Models

• Udor RBC 122K Gearbox — 22 HP heavy-duty reduction gearbox for larger plunger pumps
• Udor RH Series Gearbox — Extra heavy-duty reduction gearbox for high-power applications
• Udor S160 Gearbox — 6:1 ratio reduction gearbox for diaphragm pumps
• Udor RV Series Gearbox — Heavy-duty gearbox with multiple ratio options