Interchangeable Parts

If you had been standing by the roadside in Surrey, England in 1908, you might have caught a glimpse of three remarkable cars driving down the road.  The cars were all identical Cadillac automobiles, but they were certainly…different.

The world’s first racetrack, Brooklands, was conducting a test of a relatively radical new idea for automobiles: interchangeable parts.  Up to that time, each car had had hand-fitted parts made for that vehicle specifically.  Even two apparently identical vehicles had variations in their parts, and if one needed a part replaced, it required a skilled mechanic to alter and fit the part.

In 1908, the Royal Automobile Club sponsored a test for standardized parts.  While ten car companies were invited, only the Cadillac Motor Car Company showed up.  Three different Cadillac cars, painted three different colors, were dismantled and the parts placed in a single pile in the middle of a garage.  89 parts were randomly removed and replaced with new ones straight from the Cadillac storeroom in London.

Then, the mechanics reassembled three cars using only screwdrivers and wrenches.  The resulting cars were no longer very attractive, as each had doors, fenders, wheels, and hoods of oddly mismatched colors.  Then the three cars were driven 500 miles around the Brooklands track and the nearby streets of Surrey without a breakdown.  Cadillac was awarded the Dewar Prize, the automotive equivalent of the Nobel Prize.

This feat changed everything in the automobile industry.  Now, every car company had to rush to offer interchangeable parts.  I blame this on Napoleon.

Almost everyone in America knows that interchangeable parts are something that started with Eli Whitney and the production of guns for the US government.  I remember learning this in the fifth grade.  I think that was the last thing I learned that year, since shortly after that day in history class, I started to change my opinion of the relative ickiness of girls. 

(Actually, of course, the first true universally interchangeable parts were created when the first United States Congress convened in 1789.  There hasn’t been a pennyworth of difference among those idiots in the last 225 years.)

Eli Whitney was a fake: in 1808, he wanted the government contract so much that he claimed he could manufacture a large number of guns with interchangeable parts--and his claim seemed plausible, since he let Congress examine a few carefully selected muskets.  The congressmen took the muskets apart, piled up all the parts, stirred them around and then put the muskets back together.  Since they still worked, Congress gave Whitney the contract for 10,000 muskets.

There is only one way to truly create interchangeable parts—with machinery.  There is simply no way to rapidly duplicate precise parts by hand.  A skilled craftsman can slowly produce a limited number of parts possessing fairly close tolerances--and this is how Eli Whitney was able to fool the US government.  However, only machinery can rapidly turn out identical pieces and this form of technology did not exist when Whitney won the contract.  (This is why Whitney delivered the muskets years late, and none of them had interchangeable parts!)

In fact, not long after this, the ability to mass produce certain parts became a critical military requirement.  (And if necessity is the mother of invention, it follows that "a critical military requirement is the evil mother-in-law".)

Now, fast forward to 1810, when England was at war with Napoleon’s France.  (Ah, the good old days, when you could have a war with someone you could--even if only occasionally--actually like.)  The British government was suffering something resembling an embarrassment of riches.   The British navy was made up of 191 giant ships of the line, 245 frigates, and numerous other smaller warships--giving it over 860 ships altogether.  (And another 56 ships were being constructed.)

Not only was the navy large, it was damn good.  In several wars and countless battles, the British Navy had humiliated the navies of France, Spain, Denmark, Turkey, Algeria, Russia, and Holland.  During the period from 1792-1812, the ships of His Majesty’s navy had fought in over 200 engagements and won all but 5.  (And all of those losses were in single ship-to-ship battles, none of them more recent than 7 years earlier.)

The inevitable consequence of this incredible string of victories was that an English victory was expected by not only the English, but by the captains and crews of the enemy ships the British fought.  With this attitude, it will not be surprising when I tell you that no fewer than 170 of the ships that made up the British Navy had been captured from other countries during combat. 

This huge navy was a virtual forest of masts and rigging in Portsmouth Harbor and all of this rigging had to be constructed and maintained for the navy.   Some of the required items were pulley blocks that enabled ships to raise and lower sails, steer ships, and lift heavy cargo.  These giant pulleys were all made of wood and no two of the hundreds of thousands of them in service were exactly the same.

Between the needs of new ships and replacing the blocks of older ships, the Admiralty office was purchasing an astonishing 100,000 new pulley blocks a year. 

Marc Brunel revolutionized the Portsmouth Block Mills at the harbor by introducing machinery run by conveyor belts, powered by two 30 hp. steam engines that automated the entire process of manufacturing the pulley blocks.  The forty-five separate machines that performed 22 processes could turn out standardized blocks in three sizes--and every piece was uniform and could be used to replace a defective part of the same-sized block.  

Not only was a superior block produced, but the labor savings were enormous.  Where 110 men had worked previously to produce a limited number of blocks of varying quality, ten men using the new machinery were capable of producing 130,000 blocks a year.

The nineteenth century saw the end of the great wooden ships, as first iron, then steel monsters replaced the beautiful great ships of the line.  Sails gave way to coal- and oil-fired ships.  Napoleon died, and (sadly) France and England became allies.  Brunel’s pulley blocks fared much better.  The machinery making them was still in use during World War II, only ceasing production in 1960.