Trevithick's patent 1802, high pressure steam engine, constructed 1811 for threshing purposes at Trewithen, in use till 1879

Made:
1811 in Hayle

Trevithick's patent 1802, high pressure steam engine, constructed at Hayle Foundry, 1811 for threshing purposes at Trewithen, Cornwall, in use till 1879

This was the first steam engine built for threshing corn, and is highly likely to be the earliest surviving agricultural steam engine anywhere. It was designed by Cornish engineer Richard Trevithick, and built at Hayle Foundry, Cornwall, for Sir Christopher Hawkins to use on his estate at Trewithen. The engine employed what Trevithick called ‘strong’ steam – that is, steam at high pressure, of around 50 pounds per square inch, as opposed to the 3 or 4 used on engines built by earlier engineers like James Watt. This allowed the engines to be built smaller and more compact for the same power output, or larger and more powerful, as exemplified by the engines erected on metal mines in Cornwall to pump water from deep beneath the surface to ground level.

In 1812, Trevithick was advertising engines like this one for threshing and grinding corn and sawing wood, and prepared drawings for such a machine to be self-propelled, pre-empting the thousands of steam-powered traction engines built by many companies which made a huge impact on transport and agriculture during the nineteenth and twentieth centuries.

The engine is ‘single-acting’, meaning that the steam when it enters the cylinder pushes the piston in only one direction, with a weight on the engine’s flywheel helping return the engine to the start of its stoke again. This simple design also allowed the engine to be used ‘expansively’ without introducing any complications to its design - that is, admitting steam to the cylinder for only part of its working stroke and then cutting the supply off, allowing the steam to exert a continued (but reducing) force of its own volition while reducing the amount of steam used per stroke. This principle became commonly applied to all engines working with high steam pressures, and was a major source of economy.

The engine worked until 1879 when it was exhibited by the Royal Agriculture Society Show in London in recognition of its pioneering status. After that, it was presented to the Science Museum. The engine thus had a long life – though note that as with all old engines, there is the possibility of replacement parts being present in place of worn-out originals. The boiler may be a replacement for the original, dated approximately 1854.

Details

Category:
Motive Power
Object Number:
1879-57
Materials:
cast iron and wood
type:
high pressure steam engine
credit:
Royal Agricultural Society

Parts

Boiler, with 6 bolts & 5 nuts for securing cylinder

Boiler, with 6 bolts & 5 nuts for securing cylinder

Boiler, with 6 bolts & 5 nuts for securing cylinder, safety valve, manhole, flange for feed pipe, 2 pipes & cocks for water gauge (no glass), 2 pipes for try cocks, stays & nuts to furnace front, and brick fire wall in flue

Object Number:
1879-57/1
type:
boiler
Bearing timber for front end of boiler

Bearing timber for front end of boiler

Bearing timber for front end of boiler, presumably made in the Museum, now made up with other timbers to form a cradle for the boiler

Object Number:
1879-57/2
type:
bearing timber
Floor Timber Supporting Rear End of Boiler

Floor Timber Supporting Rear End of Boiler

Floor timber, supporting rear end of boiler and forming base of upright frame, and two upright timbers (one with brackets for feed pump and 2 coach screws), all presumed made up in Museum

Object Number:
1879-57/3
type:
floor timber
Horizontal Timber Forming Top of Upright Frame

Horizontal Timber Forming Top of Upright Frame

Horizontal timber forming top of upright frame (two pieces joined by flitch plates) believed to be original, with block carrying a pin and bolts etc for joints

Object Number:
1879-57/4
type:
frame
Inverted T Frame to Support Outboard Journal of Crankshaft

Inverted T Frame to Support Outboard Journal of Crankshaft

Inverted T frame to support outboard journal of crankshaft, believed made up in Museum

Object Number:
1879-57/5
type:
t frame
Two rod-bolts with nuts & plates

Two rod-bolts with nuts & plates

Two rod-bolts with nuts & plates, to connect /3 to /5, and iron bar for staying /7 to /5

Object Number:
1879-57/6
type:
rod-bolt
Cylinder with Column and Bearing Cap

Cylinder with Column and Bearing Cap

Cylinder with column (separate piece attached by cotter) with bearing cap but lacking bottom brass and pin for valve cam follower

Object Number:
1879-57/7
type:
cylinder
Piston and weight from lever safety valve

Piston and weight from lever safety valve

Piston and weight from lever safety valve

Object Number:
1879-57/8
type:
piston
Connecting rod with pin for lower end and brasses

Connecting rod with pin for lower end and brasses

Connecting rod with pin for lower end and brasses (damaged) and gib and cotter for upper end

Object Number:
1879-57/9
type:
connecting rod
Crankshaft with Crank & Pin

Crankshaft with Crank & Pin

Crankshaft with crank & pin, and 4 bolts, nuts & washers for securing flywheel

Object Number:
1879-57/10
type:
crankshaft
Flywheel

Flywheel

Flywheel

Object Number:
1879-57/11
type:
flywheel
Valve Cam

Valve Cam

Valve cam, in 2 parts bolted together, with grub screw

Object Number:
1879-57/12
type:
valve cam
Cam Follower Lever with Roller and Valve Rod with Knuckle

Cam Follower Lever with Roller and Valve Rod with Knuckle

cam follower lever with roller and valve rod with knuckle end (from a Cornish engine ?)

Object Number:
1879-57/13
type:
cam follower level
Spring to act on cam follower

Spring to act on cam follower

Spring to act on cam follower

Object Number:
1879-57/14
type:
spring
Lever and 2 rods for working feed pump

Lever and 2 rods for working feed pump

Lever and 2 rods with all pins etc for working feed pump

Object Number:
1879-57/15
type:
lever
Feed pump with clack body

Feed pump with clack body

Feed pump with clack body, plunger (detached) and feed pipe to boiler (detached). Pump barrel lacks one gland bolt

Object Number:
1879-57/16
type:
feed pump
Dead plate, furnace front and fire door

Dead plate, furnace front and fire door

Dead plate, furnace front and fire door

Object Number:
1879-57/17
type:
dead plate
Fourteen and a half iron firebars

Fourteen and a half iron firebars

Fourteen and a half iron firebars

Object Number:
1879-57/18
type:
firebar
Adjustable piece with centre screw to hold plug cock into its seat (plug cock not found)

Adjustable piece with centre screw to hold plug cock into its seat (plug cock not found)

Adjustable piece with centre screw to hold plug cock into its seat (plug cock not found), a brass barrel cock used as a (mocked-up?) try cock, bolts, nuts etc, coach screws, wedges, an angle piece (probably made in Museum) with an old bolt, nut & washer and a brace of iron bar (probably made in Museum). Purpose of some of the above not identified and they may not belong

Object Number:
1879-57/19
type:
adjustable piece
2 iron plates

2 iron plates

2 iron plates, one broken short, with countersunk holes, purpose not identified and they may not belong

Materials:
iron
Object Number:
1879-57/20
type:
plate
Drawing of Trevithick's 1802 patent high pressure engine

Drawing of Trevithick's 1802 patent high pressure engine

Large (A1?) technical drawing of Trevithick's 1802 patent high pressure engine

Object Number:
1879-57/21
type:
drawing