60 Pounder, Technicalities

[Old Tom]

I have been readfing an article in a WFA publication describing a 1914 model of a Mk 1 60 pounder. The text refers to certain changes in barrel construction for wartime manufacture. With these the gun became Mk1* and Mk 1 **. I also note the model had wooden spoked wheels rather than the 'traction engine' type.

My knowledge of barrel manufacture is pretty limited. Can anyone describe the manufacturing changes?

Old Tom

[nigelfe]

There are perhaps three options, one would be a solid machined barrel, I don't think this is very likely. Next would be a solid machine liner, the innermost tube. Then there are two options, either built-up with other tubes outside it or wire-bound with an outer sleeve.

[MikB]

There are perhaps three options, one would be a solid machined barrel, I don't think this is very likely. Next would be a solid machine liner, the innermost tube. Then there are two options, either built-up with other tubes outside it or wire-bound with an outer sleeve.

I've no definitive knowledge on the 60-pounder, but I think the latter would be the method more commonly used on British guns - even smaller pieces like the 13-pounder were wire-wound for about a third of the barrel-length from the breech.

Regards,

MikB

[Old Tom]

My understanding, from the description of the model, is that the first 60 pounder barrels were wire wound. I wondered what changes were made, presumeably to ease manufacture. I seem to recall the term 'autofretage' (or something like that) for 25 pounder barrels but that is much latter.

Old Tom

[calibre792x57.y]

According to 'British Artillery Weapons & Ammunition' by Hogg and Thurston the 60 pdr Mk1 was an Elswick design with a wire wound barrel. Although successful no regard had been paid to ease of production and as the need for these guns became urgent, steps were taken to improve the design for production. The Mk 1* did away with the inner 'A' tube and breech bush and simply threaded the rear end of the A tube to take the breech block. Another design by the Royal Gun Factory, the Mk1** also did away with the inner A tube but kept the breech bush in an altered form. Both these Marks were introduced in 1915 and remained in service until 1944. The Mk 2 was a major redesign but none were issued before the Armistice. - SW

[nigelfe]

Autofrettage is a technique for pre-stressing the barrel to strengthen it. It was invented by the French just before WW1 but was not used by UK (at least for field artillery) until after WW1.

The A tube was the standard UK term for the innermost tube, the rifled one, later called the liner. Larger calibres were generally built-up with tubes inserted in more tubes, and this was the normal construction of continental guns. UK always used wire bound A tubes with 18-pr and 4.5-in How. The barrel was fitted in a jacket, this was essential because it provided the interface to the recoil mechanism. The change to autofrettage monobloc construction meant that the jacket generally only went for about half the barrel length, previously jackets were full length of the A tube. Doing away with the inner A tube is nonsense, there was only one A tube and it was rifled.

[Chasemuseum]

To further confuse the unwary, the barrel, breech and recuperator is the “ordinance” this is given a Mark number. The field carriage is given a separate Mark number

For 60-pr the Ordinance is MkI, Mk I*, or MkI**. The MkII did not enter service until after the war and has the recuperator under the barrel, looking more like a 6-inch gun.

The field carriage has a separate Mark number, MkI, MkII and MkIII. The MkI field carriage was expensive and very difficult to manufacture. There is the example on display at IWM. It was normally used with wooden wheels No12. For transport the gun is hitched to the limber, the cradle is released from the front of the carriage and winched back to near the limber and lashed down with steel screw clamps. This distributes an equal load to the gun wheels and the limber wheels.

By comparison, field carriages Mk II, II* & III, the cradle is fixed to the carriage. So for transport there is ballast in the carriage trail. This makes the gun much heavier and puts most of this load on the gun wheels – hence these marks always used the 5ft steel “tractor” wheels with a 12inch track. The difference between a MkII and a MkIII, is that the latter is arranged for the barrel to be unlocked from the recuperator connecting rods and the barrel to be drawn back into the “battery” position for transport, increasing the load on the limber wheels and reducing the load on the gun wheels. A MkII* is a MkII converted to the MkIII configuration.

Most of the surviving guns in USA are field carriage MkII* or MKIII while the surviving guns in South Africa are MkI.

Regards

Ross T

[MikB]

Autofrettage is a technique for pre-stressing the barrel to strengthen it. It was invented by the French just before WW1 but was not used by UK (at least for field artillery) until after WW1.

The A tube was the standard UK term for the innermost tube, the rifled one, later called the liner. Larger calibres were generally built-up with tubes inserted in more tubes, and this was the normal construction of continental guns. UK always used wire bound A tubes with 18-pr and 4.5-in How. The barrel was fitted in a jacket, this was essential because it provided the interface to the recoil mechanism. The change to autofrettage monobloc construction meant that the jacket generally only went for about half the barrel length, previously jackets were full length of the A tube. Doing away with the inner A tube is nonsense, there was only one A tube and it was rifled.

In wire-wound gun barrels, the jacket was also needed to provide longitudinal strength - the wire obviously only provided radial strength, and the rifled A tube liner wouldn't be enough on its own.

Regards,

MikB

[calibre792x57.y]

Search me mate. As I said in the post I merely quoted what the source said. - SW

[Chasemuseum]

For the 60pr MkI there was initially an “A tube” and an “inner A tube”.

The attached extracts are from the 1921 manual but the sections in the 1916 manual are the same.

Regards

Ross T

[Chasemuseum]

With respect to field carriages

Mk I

Gun arranged for transport

Mk II*

Regards

Ross T

[Old Tom]

Some interesting stuff here. Many thanks. Not sure where the ordinance came from; sorry could not resist the temptation.

Old Tom

[calibre792x57.y]

Autofrettage is a technique for pre-stressing the barrel to strengthen it. It was invented by the French just before WW1 but was not used by UK (at least for field artillery) until after WW1.

The A tube was the standard UK term for the innermost tube, the rifled one, later called the liner. Larger calibres were generally built-up with tubes inserted in more tubes, and this was the normal construction of continental guns. UK always used wire bound A tubes with 18-pr and 4.5-in How. The barrel was fitted in a jacket, this was essential because it provided the interface to the recoil mechanism. The change to autofrettage monobloc construction meant that the jacket generally only went for about half the barrel length, previously jackets were full length of the A tube. Doing away with the inner A tube is nonsense, there was only one A tube and it was rifled.

Well it seems despite 'nigelfe's 'nonsense' the authors of my source appear to have been correct according to the handbook on the 60 pdr. Mk 1. Thanks to Ha Go T95 - Now as I was saying........ SW

[Steven Broomfield]

Out of interest, these two photographs of a 60pdr at Ploegsteert in mid-October, 1914, were taken by Lt Col T T Pitman, 11th Hussars. They come from the archives of HorsePower, the Museum of the King's Royal Hussars in Winchester.

[squirrel]

Some recoil!

[Steven Broomfield]

I'm guessing, but I think that's why it wasn't fired from the shoulder.

[nigelfe]

As I said, doing away with the inner A tube is nonsense, it's the one with the rifling (and also is the calibre), as I previously said (check your quote Sommewalker - "The Mk 1* did away with the inner 'A' tube").

Note that the wire binding was only about half the barrel length, it was a bit less with 18-pr, and the jacket is not full length whereas it was with 18-pr.

You can see why they'd want to simplify the barrel construction, it was both wirebound and built up, even if the latter was only two tubes. The interesting question is why such a complex design was adopted. You could say typical British engineering, use the most expensive solution! Perhaps it was psychological confusion, field guns were wirebound, siege and large naval and coast guns were built up, 60-pr was at the crossover, therefore a bet each way! That said the 60-pr was recognised as an overly complicated design and expensive to build.

I'd be interested to know the source of the statement that the recuperator was part of the ordnance, it is not usually the case. The recuperator had to be paired with the recoil (a recuperator gives 'run-out after recoil) and on some WW1 guns had an external oil tank as well. This lot was part of the superstructure, although with the ordnance it's also called the 'elevating mass'.

[squirrel]

I'm guessing, but I think that's why it wasn't fired from the shoulder.

The wheels would get in the way....

[Chasemuseum]

Ordnance - v - Ordinance.

My apologies I am an absolutely appalling speller.

Should the recuperator be considered part of the ordnance?

Yes but mainly No. The recuperator and the related components include a system of saddles over the barrel, with slides on a bearing surface(s) and piston assembly fixed to the breach-ring with the cylinder fixed into the recuperator box.

Design and manufacture of the saddles and the connection points on the breach-ring are part of the “Ordnance”. The rest of the recuperator assembly is normally part of the mounting.

With the 60-pr, the design of the breach-ring varies between the Mk I & II and II* & III mountings with the former not having the ability for quick release of the piston rods and latter modified to achieve this.

This creates the obvious weakness in the delineation of these nominal supply boundaries as the engineering team working on breach-ring design and the machine shops making or repairing these components belong to the “Ordnance” supply stream. Yet they are integral in this part of the change to the mounting design.

The opportunity to waste time and effort in the supply process is obvious.

Regards

Ross T

[Old Tom]

Ross T

Interesting again. No need to apologise for ordinance, if apologies are due may I offer mine for being pedantic; my dictionary says both words have the same root. The quick release of the piston rods intrigues me. Can you say why this facility was needed?

Old Tom

[Chasemuseum]

Hi Tom,

Regards the quick release of the recuperator piston rods from the breach-ring, as stated in post #7, this allowed the barrel to be drawn back into the battery position for transport, distributing the weight of the gun over both the gun wheels and the limber wheels.

Attached is a photo of a 60pr on MkII carriage in 1916 on the Somme using 12 horse draught. This has the entire gun load on the gun wheels increasing the bogging problem and also needing extra sandbags on the end of the trail as a precaution against the gun over balancing and lifting the limber.

For the technical purist – the manuals call the wheeled vehicle lifting the trail a “Carriage” not a limber. It only has accommodation for 2 projectiles and 2 cartridges and the 1921 manual has an instruction that it is not to carry any ammunition. Ammunition is actually carried in a “limbered wagon”, that is a limber that looks a bit like an 18pr limber and a 2-wheeled towed wagon that looks like the 4.5-inch howitzer ammunition wagon.

Regards

Ross T

[nigelfe]

The ordnance of 60-pr was retracted for towing, a feature also found in some later designs, in some cases this involved disconnecting the ordnance from the recoil system, (130mm M46 rings a bell here). However, this doesn't seem to have been the case with 60-pr where the complete superstructure (ie saddle and above) is slid back. Obviously if the ordnance was being completely removed then it would have to be disconnected from the recoil system.

HA Go is a bit confused in the 'naming of parts'. The saddle sits between the traverse pivot (60-pr had only limited top traverse, large switches required the trail to be moved) and supports the trunnions, rotation of which enable the ordnance to be elevated. The trunnions are attached to the cradle which has slides into which the slides of the ordnance fit. Usually the recoil system is below the ordnance in the cradle, but sometimes above, particularly in heavier guns if they do not have a very high max elevation angle (yes I know about 122mm D30), the benefit is less height to lift the shells.

In UK terminology, Ordnance (the US has its own quaint ideas) comprises the barrel and breech assembly. See pg 42 - Chap 1 Ordnance and pg 71 - Chap 2 Carriage of the 1935 edition of the 60-pr Handbook (amended 1939), the carriage components are listed as: Axletree & wheels, Trail with spade, Brake gear, Saddle, Traversing gear, Cradle, Housing gear, Elevating gear, Recoil system, Sighting. The recoil system comprises the buffer and the recuperator.

This page http://nigelef.tripod.com/gunchars.htm of my web site may help.

[Old Tom]

Thanks again, even if I am left a little confused. May I, as some long forgotten lecturer used to say, rehearse my faith on the subject in laymans terms. The 60 pounder was a weighty equipment (4.4 tons). In 1914 I believe it was drawn by 6, for want of a better word, cart horses. (Later by a Holt tractor) To distribute the weight evenly between the gun wheels and the carriage/limber wheels for movement parts of the equipment could be moved back. The potentially movable parts were the ordnance, recoil system and the cradle including elevating and traversing gear. These parts comprise the superstructure in Nigels post.

The quick release of the the pistons attachment to the ordnace implies that the ordnace alone could be moved towards the limber/carriage.This would redistribute weight to some extent but without some supporting structure would leave the ordnace 'loose', which seems undesirable for movement. However if the whole superstructure is slide back along the surface of the trail a greater redistribution of weight is achieved and the whole equipment would be secure for movement. This is illustrated in the second picture of post 11. Ross T's excellent picture with 8 horses seems to show that arrangement.

That leaves me with only one question - were there two methods of redistributing weight for movement and did one supercede the other?

Old Tom

[RodB]

The Wikipedia article attempts to give a basic but accurate overview and history of the gun and draws on reputable sources such as Hogg & Thurston and History of the Ministry of Munitions. Both discuss Carriage Mk III, stating as Ha Go states that it allowed the barrel to be disconnected from the recoil mechanism and moved back to better redistribute the weight similar to Mk I.

The problem for the Wikipedia article is that I can't find a photograph or diagram that illustrates this. Does anybody have such images free of copyright they can donate to illustrate the article ?

[nigelfe]

Moving the ordnance and possibly the cradle back to better distribute the weight when towing the gun was not notably uncommon. Of the top of my head I think the last gun to use it may have been the Soviet 130mm M46 although their 180mm may also have used it. I think another WW1 example may have been the French 155mm GPF.