A Rare Survivor - Dockside Sheerlegs
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  1. #1
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    Default A Rare Survivor - Dockside Sheerlegs

    jd-tmv1.jpg 1 jd-tmv2.jpg 2 jd-tmv7.jpg 3 jd-tmv8.jpg 4

    Large sheerlegs, with riveted iron or steel tubular legs, were prominent features in numerous dockyards from the mid-19thC.

    They were used for lifting heavy components such as boilers, engines, and guns into and out of ships. They were made obsolete by more versatile equipment such as hammerhead cranes. Surprisingly, a large set was installed in Aberdeen as late as 1911, and survived until it was blown down in a gale in 1970. Superb photos here:-

    Sheer Legs | Doric Columns

    I thought they'd all gone the way of dinosaurs, so I was delighted to come across an example in Trondheim, Norway.

    The Trondheim sheerlegs are of relatively modest size, but very impressive nevertheless. I estimate the height at about 55 - 60 ft. Some 19thC examples were up to 160 ft high.

    These sheerlegs are located in the former shipbuilding and marine engineering complex of TMV (Trondheim Mekaniske Verksted). The site has been redeveloped into an attractive location for leisure/shopping/offices, etc, while retaining many building and infrastructure from the TMV days. Unfortunately the execution suggests a somewhat unsympathetic attitude to old industrial equipment machinery, which is all too common with city authorities and developers the world over. However this is perhaps something for another thread.

    More information about TMV's history and development:-

    Trondheim Mekaniske Verksted - Graces Guide

    This includes links to zoomable photos of the site in 1952, which show that the Trondheim sheerlegs have been relocated (presumably during the recent redevelopment).

    Returning to the sheerlegs, it will be seen that the legs are pivoted on the edge of the dock, and in service they would have made to lean back to pick up the load, and to lean out over the ship to place it. The leaning was achieved by means of the rear leg (backstay), which was moved to and fro by a leadscrew. The leadscrew is about 5½" diameter. An example at Chatham Dockyard had a leadscrew 11½" dia and 85 ft long!

    The winch equipment is damaged and incomplete, but I suspect that it was originally worked by an electric motor.

    I only had time for a few quick photos, and later study begged a number of questions. Fortunately a return to the port a week later provided answers to those questions, but it raised a few more.

    I'll return with more photos later.
    Last edited by Asquith; 09-20-2019 at 10:41 AM.

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    jd-tmv15a.jpg 5 jd-tmv11a.jpg 6 jd-tmv6a.jpg 7

    Photo #5 shows the cast iron trough that houses and secures the leadscrew for the backstay.

    Photo #6: 2-speed drive to the leadscrew.

    #7 Nut attached to the back stay.

    sheer150t-3-.jpg 8

    #8 Drawing showing the one of the 'tumbling bearings' supporting the leadscrew on sheerlegs (made by Day, Summers & Co for Kronstadt in 1882). It also shows how the nut is guided in the trough. The guiding arrangement is very similar on the Trondheim crane.
    Last edited by Asquith; 09-20-2019 at 04:41 PM.

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    sheer150t-1-.jpg 9

    #9 Shows the marine-type thrust block on the Kronstadt leadscrew. I assume that the Trondheim crane originally had a similar arrangement, and that it has been cut off.

    jd-tmv16.jpg 10

    Photo #10 shows that the end of leadscrew is now welded to a plate. The fillet weld only extends round the top half. Obviously the sheerlegs have long been put beyond use. The front legs lean out slightly over the water, and will only exert a small pull on the backstay. Or, a larger pull in the event of a gale. It appears that responsibility for resisting this pull is placed upon that modest weld at the end of the leadscrew.

    I'd like to think that the leadscrew's trough is securely fixed to the ground. The bosses for the holding-down bolts at the drive-end of the trough are unoccupied, but my photos show brackets at three positions within the trough, with what are presumably anchor bolts straddling the leadscrew, acting to clamp down on the trough's internal flanges (see photo #11). A pair of anchor bolts are used to hold down the winch machinery (not sure why), the clamp being just visible in photo #6.

    jd-tmv17.jpg 11

    I couldn't find any information about the crane's history or about its re-siting, but then my lack of Norwegian is a major barrier to searching
    Last edited by Asquith; 09-21-2019 at 03:45 AM. Reason: Updated trough information

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    I've long wanted a ships derrick in front of the shop... a rig like this would do also. telephone poles for the legs, keep the apex inside the figure to limit drama on the 3rd leg.

    I wonder what the wife would say...

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    Apologies if I've posted this before, this is photo from a local sawmill that's about 140 years old in that location. There 's a railway siding at the base of this equipment and a riveted boiler at the base of the machine. It was in use until the mid 1970's when a fire broke out and burned all the surrounding wood buildings, is it a similar device?. I can go and get more detailed photos too.

    lifting.jpg








    Attached Thumbnails Attached Thumbnails lifting.jpg  

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    That would be a "stiff leg derrick". It has the ability toswing the boom, commonly by wire rope around large diameter drum or capstan at the base of the boom. It could also change the boom angle by a wire rope hoist. I remember seeing at least one at a sawmill when I was a kid.

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    Quote Originally Posted by tdmidget View Post
    That would be a "stiff leg derrick". It has the ability to swing the boom, commonly by wire rope around large diameter drum or capstan at the base of the boom. It could also change the boom angle by a wire rope hoist. I remember seeing at least one at a sawmill when I was a kid.
    It'll be gone for good soon: I hear developers are going to build a block of units on the site. Here's another photo of the derrick in the background while a transport boat is being built for the US Army during WW2 to transport materiel to New Guinea to the North.

    Stratford Heritage Trail

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    Asquith, thanks for another really interesting thread.

    -Marty-

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