Hornsby Oil Engine

An oil engine can be a touchy beast. Here are complete instructions from one manufacturer on the care and use of theirs

Hornsby oil engine

The oil engine must be set level and square to its drive, and bolted toa block of good hard concrete.


Content Tools

The Hornsby oil engine works on the Otto Four Cycle, i.e., one explosion for two revolutions of Crank. The oil is converted into vapour by being sprayed into the hot Vaporiser. The explosion is obtained by the compression of fresh air along with the vapour already in the hot Vaporiser.

A separate plan is supplied with each Engine giving particulars for erection and diameters of pipes required.

The Vaporiser Cap End is heated by lamp before starting and is kept hot by the explosions.

The Lamp is required for starting only.

The Speed is regulated by governor acting on relief valve (see Vaporiser Valve Box, p. 15), a portion of oil delivered from pump escapes and flows back to Oil-tank, thus reducing the quantity sprayed into Vaporiser, and consequently reducing the force of explosion.

The Engine must be set level and square to its drive, bolted to a block of good hard concrete.


Engineers: LINCOLN, England


Works at Lincoln and Grantham

Section of Hornsby Oil Engine

The Tank for Cylinder cooling water may be placed to suit building, but not lower relative to Engine height. Rain or soft water should be used; if water is hard, the lime deposit must be cleaned frequently from the vaporiser and cylinder water jackets. The tank must be filled well above inlet "T" value, "U" open, cock "V" shut. The water coming from top of Cylinder should be not less than 100°, nor more than 140° Fahrenheit. Quantity of water not less than 44 gallons (7 cubic feet) per brake h.p. In hot countries more may be necessary.

The pipe for adding cold water to the tank should be taken within 3in. of the bottom, and the overflow pipe should be at the top above the water circulating pipe.

The Exhaust Pipes and Silencer should be at least one foot from all woodwork, not buried, but arranged in trenches for easy access.

The Lubricating Oil for piston is most important; inferior or unsuitable Oils cause Engine to work badly by fouling the Cylinder. Oil must never be used a second time. For Great Britain R. & H. supply and strongly recommend their S.C.L. brand of Gas Engine Cylinder Lubricating Oil, and ask all users not to obtain any other quality except under their advice.

The best Engine Bearing Oil should be used for all other working parts.

Ring Oiled Crank Shaft Bearings (where fitted): 

The oil reservoir of these must be filled to the indicated level. Care should be taken that the oil is kept clean by regularly removing the sediment out of the oil wells. Examine all ring oil bearings to see the rings are working properly.

Minor adjustments of compression to suit local conditions or variations of oil can be made by moving the roller on end of exhaust lever (using the plain washer supplied). If the oil requires a higher compression or the Engine tends to cool down by the scavenging effects of the exhaust arrangements then the roller can be advanced from a central position to a forward position. If the oil requires a lower compression or the Vaporiser gets too hot through back pressure in the exhaust arrangements, the roller can be adjusted to a back position.

To adjust the Engine to suit different Oils.Only one Vaporiser is used on each size of Engine of 1 b.h.p. to 4 b.h.p. inclusive. For each size of Engine 5 b.h.p. to 30 b.h.p. we make two different vaporiser cap ends, one marked "O" and the other marked "P." The former has more heating surface than the latter, and gives a higher compression. Each Engine is sent out fitted with the vaporiser cap end best adapted to the use of the class of oil specified by the customer at the time of ordering. If no indication of the class of oil to be used has been received, then Engines for Great Britain are set to use American Refined Oil. For abroad, that vaporiser cap end is supplied which is most commonly required for the country to which Engine is going.

If customers wish to change their vaporising oil, R. & H. strongly recommend a sample (not less than 5 gallons) be sent them to test, when they will advise customers what alterations and adjustments are required to get the best possible results from it.

When vaporiser cap ends are fitted with cleaning doors the studs or screws securing these in position should be lubricated on the threads with a mixture of black lead and tallow each time the door is removed. The same treatment should be given to all studs that get hot when Engine is working.

In Frosty Weather, after stopping Engine, close cock "U" open cock "V" to empty pipes and cylinder jacket. Engines 5 b.h.p. and above, also open cock "O."

To prepare for starting Engine. Fit proper worsted wicks in oil cups where fitted on crank shaft bearings, and crank end of connecting rod, and fill with oil. Oil the following parts: Piston end of connecting rod, bearings of side shaft, skew gearing, rollers and pins on valve levers, lever bearings, governor and spindle and joints, bevel wheels and pins of levers to relief valve.

To trim the lamp, fill the reservoir of lamp through plug "A" level with plug "B," replace plugs "B" and "A," then turn cock "C" to position "STOP." Pump air into reservoir, then pour oil on cup "D" under coil, put a piece of asbestos wick in it, and light it. When well alight, turn cock "C" to position ' START,' and regulate until Oil in cup "D" burns with a clear flame. After oil has burnt out in cup D, turn cock C to position "WORK," and regulate it so as to obtain a. steady clear flame. Should the flame burn unsteadily, or on one side, clean the spray hole out with the pricker supplied, pump more air into the reservoir, and re-adjust cock "C." Occasionally take out plug in bottom of coil and allow air (under pressure) from the reservoir to blow through and clean interior of coil.

To Heat the Vaporiser, take the lid off Vaporiser cover, place lighted lamp underneath; according to size of Engine, 5 to 15 minutes should heat Vaporiser enough. Oil the Engine whilst Vaporiser is being heated.

To Stop the Lamp turn cock "C" to position ' START ' and allow air to blow through coil; this will help to keep it clean. The thorough heating of Vaporiser is most important, otherwise Engine is sure to work badly, and may stop altogether. Better double the time for heating than start with an insufficiently heated Vaporiser.To Start the Engine

In small Engines slide exhaust roller to the right to engage with double part of cam. In large Engines slide exhaust cam in direction "TO START," to engage double part of cam with roller. Set Oil Pump to give a slightly shorter stroke than No. I gauge, and put starting handle to position "SHUT," and work the pump lever up and down until oil passes freely from the overflow valve. Then turn the handle to position "OPEN," work the pump lever again once or twice ; then give the flywheel one or two smart turns, and the Engine should start readily.; The Engine can also be started by turning the flywheel backwards till it compresses the air in the Cylinder. An explosion will generally be obtained which will start the Engine forward. When Engine has got to half speed, in small Engines slide exhaust roller to the left to engage with single part of cam, and in large Engines slide exhaust cam in direction "TO WORK" to engage single part of cam with roller. After putting load on Engine, adjust stroke of oil pump to suit.

To stop the Engine, turn handle to position "SHUT."

A Self-starter may be applied when ordered for Engines 26 b.h.p. and upwards.

When a Self-starter is used see that the valve "A" on the receiver is open, and also the cock "B" on the pipe leading from the hand air pump. Put the starting lever in the quadrant at the position marked "SHUT"' and pin it there. Pump air into the receiver by the hand air pump to the pressure of say 60 or 70 lbs. to the square inch. Then close the cock B on the air pump pipe, withdraw the pin in the starting lever and get the Engine ready for starting as previously described. Place the crank a little over the dead centre in the impulse stroke in whichever direction the Engine is intended to run and then suddenly push the starting lever forward to the end of the quadrant. The Engine will start. Pull the lever right back immediately to "SHUT" position and screw down the valves on the receiver.

Before stopping the Engine at any time, pull the lever back and pin it in the hole marked "TO CHARGE," open the valve "A" on the receiver, and allow the Engine to pump air into the receiver to 80 or 100 lbs. pressure; put the lever to the end hole marked "SHUT" and pin it there; screw down the valve on the receiver and the air pressure in the receiver will be retained for the next start. If an air pump is not provided, the Engine must be started in the usual way the first time, by pulling round the flywheel, and the receiver afterwards filled each time before stopping. Periodically blow out receiver through the drain cock at bottom. The air receivers are constructed for a working pressure 170 lbs. per square inch; this must not be exceeded.

Oil pump 

When Engine is working at full power, part stamped "I" on OIL PUMP GAUGE must fit between the two round flanges "A" and "B" on pump plunger; parts marked "2" and "3" are used for adjusting pump for medium and light loads respectively. Should oil leak from pump gland it should be re-packed. Use nothing but well greased asbestos packing should be used for this purpose. Pump Plunger must work freely in its packed gland. On no account must the Engine be worked with greater oil pump stroke than No. I gauge. A continued over-supply of oil induces carbon deposit. See that the oil pipe from pump to Vaporiser has a gradual rise from the pump.

Running light or nearly so for long periods. When Engine is to run light for long periods the stroke of pump must be reduced so that governor occasionally acts on the relief valve. The vaporiser thus gets a small charge of oil each time and prevents it from cooling without reducing speed of Engine. The cock "U" can also be partially closed, to keep the Cylinder warmer. On Engines 5 b.h.p. and upwards the cock "O" may be closed. Above remarks do not apply when work is intermittent.

Skew Gearing. If the crankshaft is taken out, be sure that the Skew-wheel Gearing is afterwards put together. If the Air or Exhaust Valves open or close at the wrong time, take off the nut, which should be screwed up tightly on end of cam shaft, and see that the chisel cuts on the shaft and skew-wheel are opposite.

Engines must not be overloaded nor the Oil reduced so much that they run below the speed they are set for. This causes pre-ignitions, and the Vaporiser gets too hot, causing the Engine to lose power. Where Engines are driving dynamos charging accumulators, suitable resistances must be arranged in the shunt circuit so that the above may be carefully observed.

Air and Exhaust Valves should be ground with flour of emery and water if air leaks past. The cam rollers should not quite touch the cams when the projections are on the top. In replacing the Air Valve, take care to tighten the Nuts equally. Apply air valve seat gauge and make the space between flanges equal all round.

Vaporiser Valve Box contains the vertical relief valve regulated by governor as explained above, and a horizontal back-pressure valve. If, on pressing down the relief valve by hand, vapour should issue from the overflow pipe, the horizontal valve leaks. The cap must be removed and valve turned on its seat a few times to dislodge any dirt. If it still leaks it must be ground with a little of the finest emery and water, and great care must be taken in replacing it.

Clean the Filter occasionally: it may become clogged with dirt or gummy oil. Should level of oil get below the filter, pump will draw air in, and Engine stop working. After refilling oil tank, work pump by hand for sever minutes, holding open relief valve to expel the oil remaining in pump and pipes. Cock on filter is to be use only for testing filter.

Cylinder and Piston. Should the piston become dirty or sticky by using unsuitable lubricating oil, or should there be a leakage of gas from it, it should be taken out and cleaned thoroughly.

Piston Rings should not be taken off for cleaning purposes, but the piston end should be allowed to stand all night in a bucket of Petroleum. If a ring is set fast it can be released by pouring methylated spirit into groove. If necessary to remove a piston ring, lift the point of ring, then take a piece of thin flat steel or tin and push it under the ring, slide it round the piston; then slip in another piece, following on until four pieces are under the ring, when the ring will have sprung to the size of piston and will easily slide off.

To Fit New Rings. Before fitting rings on the Piston, ease the plain end of ring with a file until it goes into the Cylinder, as rings are always sent slightly large to allow for any wear that may have taken place in the Cylinder. Ring should then be put on Piston in usual way.

Special Hints

Do not pump too much oil when starting Engine, it cools Vaporiser unduly. Use lamp again if Engine does not start easily.

To test compression, turn flywheel forwards. If elastic resistance due to compression of air continues to be felt then air and exhaust valves and piston rings are not leaking.

When spray holes become partly blocked up, clean with rymers in tool box, but do not enlarge them. This is most important. Also frequently remove deposit out of beck under spray pad. Generally see that Engine is kept clean and free from dirt.

Take off Vaporiser cap end occasionally to ascertain that it, and the neck through which the Oil is injected as well as back part of Engine, are clean inside.

See that Crank end of piston is clean outside and properly lubricated. If dirty at that part, it should be taken out for cleaning the rings.

To test spray.

Detach valve box from Vaporiser, but not from the pump delivery pipe, then work pump by hand. If no oil is discharged the filter cock should be opened to see if the filter is choked and consequently needs cleaning. If filter is clear then take down the vaporiser valve box and test the pump. After pumping vigorously for some time in order to expel any air from the pump or pipes, the slightest movement of the pump plunger ought to cause a corresponding delivery of oil past the thumb held over the mouth of the pipe. If the pump still fails then the gland packing should be looked to and the valve examined and re-seated if necessary, or if corroded must be renewed. The Oil Spray is correct when it works without dribble and ceases immediately when the plunger comes to rest. 

Governor joints and spindle must be clean and able to move freely. It will not work properly if pump gives irregular supply of oil. It is working properly when it is constantly moving slightly up and down.

If Engine Thumps, tighten Connecting Rod on Crank Bearings.See that the flywheel keys have not worked loose.

Spare Parts: When ordering, the letters and figures on the castings should be given. If forgings or springs without marks are required, a description and slight sketch will prevent mistakes. The size and number of the Engine and date supplied should always be given.