Paxman VP185 Technical Specification
as at 2004

This page gives engine data and the technical specification of the VP185 as published in a MAN B&W Diesel brochure circa 2004. The brochure contains separate data sheets, dated 11/2004, for Marine Propulsion, Marine Auxiliary and Off-shore, Rail Traction and Power Generation applications.

On another page of this website there are VP185 specifications announced in 2012.

A brief history of the VP185's development can be found on the page Paxman Diesels since 1934.

Owners and operators of VP185 engines should not rely on the information given here (see Disclaimer) but seek the correct information about their particular engine(s) from MAN Diesel & Turbo UK Ltd, the current owners of the Paxman business, at their Colchester Business Unit.

Key Data
7.46 tonnes (dry)
10.58 tonnes (dry)
(@ 1950 rpm)  
up to 2610 kWb
up to 4000 kWb
2175 / 2971 / 1660mm
2178 / 3798 / 1450mm
Basic Parameters
Cycle:4 stroke
Bore and Stroke:185 x 196mm
Mean Piston Speed:  11·8 m/s @ 1,800 rpm
Standard Rotation:Anti-clockwise looking on the drive-end.
Aspiration:Two stage turbocharging, intercooled and aftercooled.  
Fuel Spec:BS2869 Class A2 or equivalent.
Standard Equipment (for all applications)

Engine mounted turbochargers
Engine mounted water cooled intercoolers and aftercooler
Engine driven primary and secondary coolant pumps
Engine driven lubricating oil pump
Heat exchanger/oil cooler
Lubricating oil pressure-relief valve
Lubricating oil filters
Crankcase explosion doors
Fuel oil filter
Overspeed trip
Electronic speed governor
Thermostatic valves for jacket water and lubricating oil systems
Standard paint finish

Technical Specification


This is cast in high strength spheroidal graphite iron, and is a robust and lightweight design. In the lower portion of the crankcase the underslung crankshaft is supported by main bearing caps which are double cross bolted to the deep side faces of the casting. In addition the vertical main bearing studs are hydraulically tensioned and the entire arrangement provides a strong and stiff core for the engine. Generously sized crankcase doors are provided to give access to the connecting rods and crankshaft for in-situ servicing. The crankcase supports the remainder of the engine's components to provide a self contained power unit.

Piston & Liner

The piston is a monoblock design manufactured from spheroidal graphite iron. Piston cooling is achieved using a lubricating oil cooled gallery under the crown, behind the compression ring groove and much of the second ring groove. The oil feed is via accurately aligned standing jets mounted in the crankcase. The pistons run in wet liners made of centrifugally cast high grade cast iron. Each liner has a top flange which sits on the flat top deck of the crankcase. The liner is held between the crankcase and the cylinder head at the liner flange. The lower support for the liner is arranged to be high in the crankcase and incorporates two 'O' ring seals and a large 'wedge' ring.

Connecting rods

Side by side connecting rods are made from high-strength forged steel. The rods are fully machined to give strength and weight consistency between individual rods. After machining they are ferritic nitro-carburised. The large end is obliquely split to allow the rod to pass through the liner for assembly and overhaul. This permits rod and piston removal from the top of the engine without the need to remove the engine from its mounts.


The crankshaft is a fully machined steel forging, gas nitrided for maximum strength and long wear life. Counterbalance weights are bolted to the crankshaft on every throw to reduce the out of balance caused by the connecting rods. The generous overlap between crankpin and main bearing journal provides a high degree of stiffness. Torsional damping is by means of either a tuned damper (18VP185), or a viscous damper (12VP185), fitted to the free end and totally enclosed within the free end casing.

Cylinder heads

The cylinder heads are manufactured from high strength compacted graphite iron and have an internal configuration that ensures maximum flame face stiffness and high cooling efficiency. They are mounted individually and can be removed for maintenance without disturbing adjacent heads. The air and exhaust ports have been optimised aerodynamically to maximise the efficiency of cylinder charging and scavenging. Each cylinder head carries two inlet and two exhaust valves, and a centrally located unit pump injector.

Camshaft & valve train

A single camshaft located in the centre of the engine vee provides the actuation for all valves and unit pump injectors. The 90° vee engine configuration allows the camshaft gear to mesh directly with the crankshaft gear, so eliminating the need for an idler gear and providing a very stiff drive to the fuel injection equipment. Large base circle cams coupled to high rates of lift give the essential characteristics for good combustion and low emission levels. The camfollower, push rod and rocker lever feature maximised stiffness consistent with minimised associated mass.

Exhaust system & turbocharging

The VP185 has a passive two-stage turbocharging system with intercooling and aftercooling. No valves or electronic controls are needed thereby maintaining the engine's central theme of simplicity and reliability.

All of the exhaust manifolds are contained in water cooled gas tight casings. The turbochargers are mounted directly into the side wall of water cooled turbocharger housings. The turbine side of the turbochargers and all exhaust ductwork are contained within the water cooled housing. The total arrangement of manifolds, turbochargers and housings gives the engine a gas tight system with cool exposed surfaces, an important safety feature.

The turbochargers are of cartridge type and may be readily replaced when required. The oil feed and drain lie within the turbocharger housing, avoiding the need for external pipework.

The turbochargers are arranged in groups of three comprising one high pressure and two low pressure machines.

Exhaust gas from the engine is relayed to the high pressure turbines. The exhaust from each high pressure turbine splits and drives two low pressure turbines before passing to the engine exhaust outlet.

Incoming charge air passes through the low pressure compressors and is relayed to the air intercooler(s). The air is then taken to the high pressure compressors, through the air aftercooler and on to the engine.

The air aftercooler is of passive split circuit construction, and is designed to maintain air manifold temperature at part load and prevent ignition delay. Air filter panels are on-engine mounted. Alternatively, a ducted air intake may be arranged if required.

(For more details see the page on VP185 Turbocharging Arrangements.)

Lubricating oil system

The engine is of the wet sump design with a gear driven externally accessible oil pump. For the 12VP185 twin element filters are standard for marine applications. The industrial engine may be offered with either a Simplex filter or an off-engine mounted Duplex system. On the 18VP185 a triple element filter is fitted as standard on all applications. The oil is cooled by a plate type oil cooler similar in construction to the heat exchanger, the temperature being controlled by a bypass thermostat. For most applications the oil cooler is mounted on engine providing a complete engine power unit and avoiding the use of connections to off engine equipment. Some flexibility in system design is however available to suit customer's special requirements.

Gear train

The gear train comprises carburise hardened and ground gears located in a lightweight cast aluminium casing at the free end of the engine.

The crankshaft gear meshes directly with the camshaft gear. Additional drives are arranged for the gear driven oil and coolant pumps, and for the governor actuator.

The fuel lift pump is mounted on, and driven through, the oil pump.

Fuel injection system

A combined fuel pump and injector, known as a unit pump injector offers a minimum trapped volume with an associated high rate of pressure rise.

The maximum injection pressure of 1400 bar, coupled with a high injection rate gives good combustion characteristics with low emissions and low fuel consumption.

The unit injector avoids the use of any exposed high pressure pipes and joints, and this is a distinct safety feature inherent in the VP185 design. The unit injectors are rack controlled via a linkage operated by the engine mounted actuator.

Fuel filters

In standard form the marine propulsion and auxiliary engines are fitted with duplex fuel filters in a position which affords easy access for maintenance staff.

The industrial engine has an option of either simplex or duplex depending on the application. Low pressure fuel oil is delivered via the fuel filters to the unit injectors from a gear driven fuel lift pump.

Cooling circuit

The cooling system is divided into two circuits designated primary and secondary.

The primary circuit runs at relatively high temperatures and is based on the engine housing water circuit, and provides hot water to keep the engine warm which helps to maintain steady combustion.

The secondary circuit runs at a lower temperature and is the key to achieving a sufficiently low lubricating oil and inlet air temperature in hot environments. The primary and secondary coolant is circulated around the engine by engine mounted gear driven centrifugal pumps. In general two basic cooling arrangements are offered, designated marine and industrial, although specialised arrangements can be tailored to suit the particular requirements of the application.

Heat exchanger

A single plate type oil cooler/heat exchanger unit is fitted on marine applications. Its close proximity to the respective pumps minimises pipe runs and allows the engine to be supplied as a finished power unit.


The standard marine engine is supplied with the Regulateurs Europa digital Viking 2500 governor and the Regulateurs Europa 2231 actuator with the option of ball head back-up.

The system offers a high response rate and close control of the engine coupled with a range of other control functions. For industrial applications and marine generators the Woodward UG8 actuator and 2301A speed controller are fitted as standard with the option of load share. As an option industrial engines can alternatively be fitted with Regulateurs Europa or Heinzmann governors.

All governing systems can be integrated into larger distributed control schemes.

The governor actuator is located in the centre of the vee at the free end of the engine, and is gear driven via the engine camshaft. The actuator is controlled by the off engine electronic control system.

Engine protection

The engine is fitted with alarm and shutdown switches which operate in the event of low lubricating oil pressure and engine overspeed.

Shutdown on overspeed is effected not only by closing the fuel racks, but also by governor independent air shutdown valves, which cut off the charge air supply to the cylinders. This system will protect the engine in applications where the charge air contains combustible gasses.

Alarm and shutdown functions can be tailored to suit individual requirements. A comprehensive data collection and monitoring system can be supplied which is capable of communicating with any ship control, DCS or central system as desired.

Page updated: 18 Aug 2017 at 14:31