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My Scotch Derrick Crane, homemade crane

Warning - building a homemade crane is potentially dangerous. Do not try to build one without fully understanding the principles involved in safe construction and operation. Failure of a crane (even a proper manufactured one) can result in serious or fatal injuries.

A Scotch or stiff leg derrick crane is a very simple type of crane which were used widely in the UK until the mid twentieth century.  You see quite a few still in use in boatyards and one or two around in quarries.  In other parts of the world where hard graft has not been outlawed by desk driving safety freaks, derrick cranes are in use and manufacture doing some serious heavy lifting . See the links below for more information.

On the moors, near where we live I discovered a couple of old abandoned quarries which still have the remains of derrick cranes. I was quite interested in these and how they worked and how much they could have lifted. The pictures below show the remains of these two cranes.

Derrick crane remains

This old derrick crane is on the north side of Caradon Hill. The mast is about 12 inches square. Picture shows pivot at top of mast.

Derrick crane

There's less left of this derrick but the top of the mast is still visible.

The basic components of a Scotch Derrick crane are shown in the following crude diagram, I never took much notice during "Technical Drawing" lessons at school!

Derrick crane

A = Boom, B = Mast, C = back stay or stiff legs, D = Sills, E = rough position of winches.

When I was a kid we had a house in Surrey and next door lived a chap called W A Sayers who had a crane building business.  We moved away when I was one (not quite old enough to take an interest!) but when he died, his wife (who had kept in touch and knew I was interested in engineering) gave me some of his old books, a load of nice callipers, a plumbline and a beam compass which he must have used for his work.  One of the books was, "Hoisting Machinery" by W H Atherton published in 1940.  It details all types of cranes such as Goliaths and Derricks and from it I was able to get the basic information for my homemade derrick crane.

The final motivation to build it came in 2001 while I was doing some dry stone walling.  Some of the granites I was using weighed as much as 400kg and with the ground being soft earth prying them into position with a crow bar was nearly impossible. Therefore my crane project was born, a small working version of the proven age old design.  The materials cost about £60 at the time and the crane took a few evenings to build.  Luckily it tipped with rain that week so I had a good excuse for being in my workshop.

Scotch Derrick Crane

Here it is just after completion.  Note the iron work holding the wooden sections together, the counterweights and the two lever action winches which I initially used.  The crane made the task of moving and positioning the big chunk of granite easy.  It was off the ground by about 8 inches although it's a bit hard to see in the picture.  I had to move quite a number of these big rocks, so the work of building the crane was worth it. 

The crane is built of 4" by 4" tanalised timber.  I wanted it to be able to handle up to about 500kg with the jib near the mast and about 200kg at full reach. W H Atherton gives suggested dimensions for a wooden derrick capable of lifting 1.5 tons as Mast, length 16ft, section 8" x 8" and Jib length 25ft, section 6" x 6".  So my crane was a bit over engineered, but that is fine by me. Atherton also suggests that as a good rule of thumb, the jib should not be much more than 1.5 times the height of the mast.  My cranes jib is actually twice as high as the mast.  If you see the one at Blists Hill in the picture below, the jib appears to be just a bit longer than the mast. I used a rear hub from a car as the pivot for the bottom of the mast.  A plain bearing would be fine but the taper bearings of the car hub were convenient and make for easy slewing.  The wooden parts were joined using coach bolts and metal brackets made from steel flat bar.  I basically copied the design I had seen on the remains of the quarry cranes.  Many derricks were of lattice steel construction but any poles or steel could be used provided they are strong enough and not rotten.

To see some modern Derrick cranes Click here or Click here

Scotch Derricks were often permanently fixed using concrete or masonry foundations and anchorages.  My derrick crane is movable so I set it up on sleepers and used counterweights to hold it down.  These were a couple of piles of concrete paving slabs. Counterweights can be made from drums of water.  1 litre of water weighs 1 kilogramme so it is easy to establish that you have got sufficient weight.  When setting up the crane I made sure it was all level and on solid ground, spreading the weight with various strong pieces of timber.  Initially I tested it using two hand operated pulling winches, but now I have two hand operated trailer type winches. The crane needs two winches one for raising or lowering the jib and one for hoisting. Strictly speaking, the cheap winches shouldn't really be used for lifting but with care they are alright for my project. It always pays to stand somewhere other than under the loaded jib of any crane and I keep the children and onlookers well clear.  For a bigger or permanent derrick some tested worm drive winches would be safest.  I did toy with the idea of building some powered winches but for a crane of this size it is impractical. The hand winches fit in with the cranes simple design and mean its reliable operation is not affected by damp spark plugs and other such annoyances! 

Although the derrick crane is not mobile it does have a reasonable reach and can move a load through almost 270 degrees.  It would be good for sinking a well or a mine shaft in the garden or for hoisting equipment or materials up a large retaining wall!  It would be great for anyone living by a harbour who wanted to hoist a dinghy out of the water.

Important Update 15/09/08

I have been talking to Clemens from Germany about my crane and he has pointed out a mistake with the way I built it. I connected the winch cable to the jib too near the bottom. It should be connected at the top. I obviously knew this as that is the way I drew it in the diagram but in my enthusiasm to get it finished, this subtle but crucial difference crept in. See the diagram below for clarification. Jib wire should go from top of mast to top of Jib not half way up it!

Derrick crane

Derrick crane

A Derrick crane on the Isle of Portland.  The whole place is one big quarry and there are derricks everywhere.  There's even one set up as a monument on the main road in.

Derrick crane

Here's a derrick crane I photographed at Blists Hill Museum near Ironbridge.  It wasn't on display and the wooden fence was in the way but it was a complete example .

Check out the Plant Photo Gallery for pictures of more cranes.