Kelvin Diesel Model T General Description

General Description

    The Model T Range of Kelvin Diesel engines are of the four stroke cycle, direct injection, vertical, in-line, cold starting type, the series consisting of 3, 4, 6 and 8 cylinder units developing 30 h.p. per cylinder at 1000 r.p.m. naturally aspirated, and 40 h.p. per cylinder at 1000 r.p.m. when turbocharged.

    Designed primarily as marine propulsion units, they incorporate as an integral part of the engine, a Kelvin hydraulic reverse reduction gear for which reduction ratios of 3 1/3: 1, 2 1/2: 1 and 2: 1, giving tail shaft speeds of approx. 300, 400 and 500 r.p.m. respectively, are available. Using the same gear layout, 1:1 ratio gearing can be provided in place of reducing gears, to give reverse gear action only.

    The engines can be built to either hand of rotation. The crankshaft of the standard unit rotates anti-clockwise looking on the flywheel end from aft, and its gearbox output shaft turns clockwise to drive a right hand propeller.

    In a twin screw installation, using outward turning propellers, the standard engine is to starboard and the reverse rotation engine to port, each one having its instrument panel and governor speed control lever to the inboard side, for ease of control from a central gangway

    Combining compact design, rigid construction, ease of accessibility, economy of operation and smooth running all of which are necessary attributes of a marine engine, a Kelvin Diesel of the Model T Range offers to the owner a reliable unit that guarantees years of satisfactory service with low maintenance cost,


    The main structure of the engine consists of a crankcase with removable sump, separate twin or triple bore cylinder blocks incorporating renewable wet type liners, and individual cylinder heads, one for each cylinder. The crankshaft, which is under slung within the crankcase, runs in thin wall type copper lead main bearings housed in spheroidal graphite cast iron bearing caps, one of which is located on each side of every crank.

    Each bearing cap is secured in position by two high tensile steel tension studs which pass from the crankcase through the cylinder blocks and heads, rigidly binding them in place and sustaining the main forces of the engine. Intermediate nuts are provided on the tension studs for holding down the cylinder blocks and when two or more blocks are used they are bolted together. Each pair of tension studs are shared between adjacent cylinder heads, the clamping action of the nuts being distributed by steel cross bars which bridge the slight gap between the heads. In addition to these cross bars, each head is provided with three high tensile bolts clamping the individual heads to cylinder blocks. A solid copper joint is fitted between each head and block.

    Pistons are of aluminium alloy and have three compression rings, the top one of which is chromium plated on the periphery and two oil control or 'scraper" rings. The connecting rods, which are carbon steel stampings, have four bolt fixing at the lower end. Connecting rod bushes are of the thin wall steel back type, the gudgeon pin bush lining being bronze and the crankpin or "big end" bush, copper lead. The piston and connecting rod assemblies can be withdrawn upwards through the cylinder liners.

Fuel System and Governor

    Large inspection doors in the crankcase permit access to the bearing cap nuts, connecting rod bolts and the internal parts of the lubricating oil system, an advantage in this connection being that both oil strainer and oil pump can be removed through a crankcase door without difficulty.

    This access, combined with the under slung crankshaft arrangement is an important feature of the design since one or more of the main bearings can readily be withdrawn for inspection without interfering with the engine installation.

    Drives to the camshaft, fuel pump, engine mounted generator(s) and other auxiliaries if fitted, are effected by spur gearing in the timing case at the flywheel end of the engine. The front end case also houses a gear train driving fresh water pump, sea water pump, bilge pump and tachometers.

    In accordance with Kelvin design, all parts likely to be exposed to corrosion such as crankcase, sump, cylinder blocks, inlet and exhaust manifolds, cylinder heads, rocker blocks and covers are of cast iron to ensure maximum life. Rocker covers of aluminium alloy can also be supplied, if specified.

    Block type fuel pumps incorporating fuel lift lumps are used on Model T engines and a combined fuel filter, water separator is supplied. Injection is direct, through four hole nozzles into the combustion chamber, which is a semi-toroidal shaped bowl in the piston crown.

    Permanent alignment of fuel pump and governor is ensured by having the fuel pump stool cast integrally with the crankcase.

    The Kelvin hydraulic governor, coupled to the fuel pump, provides control of the engine over the complete speed range, and embodies safety features to prevent the engine over speeding, running back, or operating when the governor is not sufficiently filled with oil for proper control.


    Lubrication of the engine is by a wet sump system, the sump, which is webbed internally for strength, being fitted with closely pitched studs to prevent oil leakage at the crankcase joint.

    Oil is drawn from the sump through a wire mesh strainer by a gear type oil pump driven by the main timing gears. The output from the pump is piped out of the crankcase to the full flow lub. oil filter, engine oil cooler, oil distributor, relief valve and back through the crankcase wall to the oil gallery which connects the main bearing caps.

    From the bearing caps, the oil is fed to the journal and big end bearings. Gudgeon pin lubrication is by splash. Camshaft bearings and rocker gear are served by forced lubrication.

    A hand pump which is mounted on one of the crankcase inspection doors, is supplied for priming the lubrication system prior to starting and can also be used to discharge the sump oil.

    The full flow lubricating oil filter provided in the system incorporates an automatic bypass to permit a continual flow of unfiltered oil should the element become choked. An additional filter complete with changeover valve arrangement to allow elements of one filter to be cleaned or changed with out interrupting the oil flow can be supplied if required.

    Two lub. oil pressure gauges are supplied with each standard engine', one being fitted to the engine mounted instrument panel and one to a wheel house instrument panel. The relief valve fitted to each engine oil system prevents excessive pressurization.

Engine Cooling

    The engines are cooled by a closed circuit, thermostatically controlled fresh water system. The heat exchanger, which also acts as header tank for the system, includes a section for engine oil cooling and the complete unit is cooled by a sea water pump, the stroke of which is adjustable to suit varying sea temperature conditions.

    An identical pump, clutch operated and with fixed stroke to give an output of 18 g.p.m., at full engine speed, is mounted on the engine for the purpose of bilge discharge or deck washing, but can also be used as an optional means of cooling the heat exchanger through piping fitted as standard on the engine.

Front End Drive

    The standard engine is provided with a 2 1/4" diameter pulley shaft, running at engine speed, situated at the forward end of the engine and with a capacity of 80 h.p. at 1000 r.p.m. For applications where a higher powered drive is required to operate, say a cargo winch when the vessel is not under way, special arrangements can be made on receipt of details.

    In place of the constant running pulley shaft as provided with the standard engine, a hand operated, enclosed, friction clutch capable of transmitting up to 45 h.p. at 1000 r.p.m. can be fitted, for use as a winch clutch on fishing vessels or for other applications. In addition to the engine room control of this clutch, remote control by chain linkage can also be supplied.

Inlet and Exhaust

    The inlet manifold is built up in sections, each of which is bolted to a cylinder head. The naturally aspirated engines of the range incorporate an efficient Kelvin air silencer mounted on the end of the inlet manifold. The Model TS.4 utilizes the same type of silencer but mounted on the intake side of the turbocharger. In the case of the TS.6 and TS.8 engines, an air filter of the oil wetted maze type is fitted to the turbocharger intake.

    The water cooled exhaust manifold has a single outlet to a dry exhaust system, if the engine is naturally aspirated, or to the exhaust driven turbocharger if the engine is turbocharged.

    Piping, silencer and other fittings, as listed in the individual engine leaflets, are supplied as standard dry exhaust equipment.

    Wet silencers, incorporating the principle of exhaust gas and sea water mixing before overboard discharge, are also available if preferred.


    The standard means of starting the engine is by electric motor engaging with a gear ring on the flywheel. A 6", 24 volt electric starter is standard supply, but alternative and additional arrangements are available, including air starting by motor, hand operated hydraulic starting and 'Hansa' film starting.

    There are positions on the engine for two starters permitting the fitting of a standby electric starter or an air starting motor in addition to the standard starter.

    Batteries are normally charged by an engine mounted, gear driven, 24 volt dynamo or generator of which several sizes are available with outputs ranging from 38 to 70 amps. One generator is supplied as standard equipment with each engine but a second drive position is available should an additional generator be required. A separate control board or voltage regulator is supplied with each generator.

    The starter battery capacity suitable for most of the Model T range is 220 amp/hr. but for the T3 and T4 engines 160 amp/hr. is adequate.

    Batteries are not included with standard equipment, as usually they can be obtained locally thus avoiding the possibility of damage in transit, but they can be supplied, without delay, on request.

Reverse Gear

    The hydraulic reverse reduction gear which is an integral part of the engine, is fitted with twin multi-plate clutches, one for ahead and one for astern action, the power being transmitted by ball and roller bearing mounted shafts.

    Irrespective of the gear ratio used, the clutches rotate at engine speed. Full power is available for ahead and astern running and the propeller speeds are equal in each direction.

    The reduction gear assembly incorporates two crown shaved pinions, in mesh with a ground reduction wheel, the gearing being of the straight tooth spur type. Pinions and wheels are of case hardened nickel alloy steel.

    A steady neutral condition is maintained without the use of a brake, as frictional drag, transmitted to the reduction pinions from bearings and clutches, is equal and opposite from ahead and astern units.

    Two sizes of reverse reduction gear, designated RGl2 and RG32, are manufactured for use with Model T engines. The RGl2 gearbox is used with Model T3 and T4 engines of all ratios and also the direct drive (1:1 ratio) versions of the Models TS4 and T6. The R632 gearbox is used with the remaining ratios for TS4, T6 and all ratios of TS6, T8 and TS8 engines.

    Propeller thrust is absorbed within the gearbox, the load being transmitted to a double thrust type ball bearing, which is situated at the forward end of the gearbox output shaft. It has ample load capacity to deal with thrust from all designs of propeller.

    The lubrication and hydraulic system for the reverse reduction gear is entirely self contained, with its own filter, oil cooler and pump. The gear type oil pump is gear driven from the astern clutch shaft and the complete pump can be easily removed for service purposes. The oil cooler is situated in the suction line to the engine sea water pump. As in the case of the engine, a relief valve is fitted to the gearbox oil system to control oil pressure.

    In the event of a loss of oil pressure in the reverse gear hydraulic system, an emergency drive is provided whereby it is possible to mechanically lock the ahead clutch in engagement.


    The standard set of Kelvin remote controls as listed in each engine leaflet covers the requirements of most installations. Engine and gearbox control is by two separate levers which are interlocked in the Wheel house Control Bracket in such a way as to prevent changing or engaging gears at excessive engine speeds. The gear or clutch lever can be moved only when the speed lever is in the range from "slow" to "very slow".

    Linkage is of the rod and lever type, all shafts and connecting runs moving in graphite impregnated bushes that require no external lubrication.

Single lever controls are also available and details can be had on application.

    A set of instruments mounted in a polished wood panel and duplicating the engine set is provided with the control equipment. Should the length of the connections to these instruments exceed 30 ft., we suggest as an alternative, the use of an electric tachometer and a warning system for low oil pressure and high water temperature alarm, these items requiring only electrical connection between the engine and wheel house and are therefore less liable to inaccuracy.

Shafting and Stern tube

    We can supply from stock a standard range of stern gear suitable for vessels of wooden construction. A bronze tail shaft runs in a water lubricated cutless bearing incorporated in a brass stern tube, at the inboard end of which is situated a gland packed stuffing box. Our standard equipment also includes a steel intermediate shaft with a shaft bearing.

    Propellers supplied as standard are primarily designed to suit fishing vessels but when the engines are required for other applications, suitable propellers can generally be obtained within the delivery period of the engine, provided adequate information regarding the vessel is supplied.

    As a general guide, propeller diameters as shown in the engine leaflets should be increased by about l0%, if the vessel is for towing duty or is of the heavily built, slow speed type. Where the aperture is restrictive in size, propellers of reduced diameter about l0% less than the listed sizes can be obtained.


    Included with the standard equipment are the necessary seacock hull fittings and piping for the engine cooling water connections. Bilge pumping and deck washing equipment incorporating bilge strainers, suction valves, discharge valves, deck washing hose with fittings and all piping are also supplied when full standard equipment is specified.

    Many other items of alternative and additional equipment, details of which can be found in the catalogue leaflets, are available and our many years of experience in planning installations are at your service.

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