Serial No. 288869
| Manufacturer : | Ruston-Hornsby, Lincoln, England |
| Model : | 1 HR |
| Fuel : | Diesel, gas oil, kerosine, or other light distillate |
| Ignition type : | Compression (diesel) 4 stroke cycle |
| Output : | 5.5 HP @ 550 rpm |
| Cylinder size : | 4¼" x 8" |
| Production period : | Feb 1938 to Dec 1961 |
| Notes : | Originally supplied to Watford Technical College in
January 1950 and rescued by Philip Thornton-Evison minutes before the scrap man
would have taken it. The 1HR is the smallest of Ruston's range of cold starting diesels whcih go right up to 78 HP in single cylinder format (size 10 HR). |
This is a 5.5 HP single cylinder, horizontal, open crank, cold starting diesel engine similar to my Ruston-Hornsby AP engine, but more robustly built to suit the compression ignition mode of operation. As supplied to a tecnical college, these engines were fitted with a brake drum to apply variable loads to the engine whilst thermodynamic measurements were made.
Flywheel dilemma
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The general arrangement of the standard 1HR engine shows 2 spoked
flywheels of 24" diameter. The college engine however, was fitted with a
standard flywheel on the "near" side and a brake drum on the "far" side. To facilitate the college installation, the crankshaft has been shortened leaving no room for a drive pulley on the "far" side, even if the ugly brake drum is replaced by a standard flywheel (if one of the correct size could be found) . With a flywheel fitted on the "near" side there is only room for the starting handle, limiting the power take-off point to the flywheel rim. |
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Here are a few shots of my engine (click the pictures for a larger image and click the return button on your browser to return here) -
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This is the 30" diameter brake drum - water was poured into the rim
to cool the drum as it was braked by a steel band - the friction would heat the
water to boiling point on a long test. Below, left is the cylinder head end with the fuel pump and glass oilers removed for safekeeping. Below, right is the camshaft, governor and numberplate. |
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| The 24" flywheel is removed here to see how the engine would look with a single, larger flywheel (try to imagine spokes and a pulley on the crankshaft on the near side) |  |
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The linkage shown here is connected to the piston skirt and transmits piston motion to the indicator (not purchased with the engine) via the small pulley attached to the bracket on the front of the cylinder cover. |
I am wondering how the engine would look if configured like one of the larger HR series engines with a single heavier than standard flywheel on the "far" side. Although not strictly to standard specification, this would permit a drive pulley to be placed on the camshaft side, and give a similar appearance to Ruston-Hornsby IP and OK engines of similar output as shown below -
| 3.5 HP OKE engine |  |
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This is a 5HP IP (Industrial Paraffin) engine |
| A 7 HP IP engine |  |
Does anybody have a spare flywheel of approximately 3 ft diameter, 3-4" face and bored for a 2" crankshaft?
A quick glimpse of how it looks at present - it does run, but starting is not easy with only one flywheel. The bright parts are in process of being winterised - treated with rust prevention fluid and wrapped in clingfilm to keep the tinworm at bay.
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