Prime Movers: When Self-Propelled was Uncommon.

[futon]

There seems to be several kinds of prime movers. Maybe they still exist today in modern military forces but as a different name. But during WW2 and before it, they were more common.

Some where only wheeled, some were fully tracked, some were half-tracked. The most common task seemed to be for hualing around guns, be it artillery, anti-air, or anti-tank guns. Maybe some were meant for towing a specific piece of equipment while maybe others were generally tow anything. 

What are the most notable prime movers?

[Tim the Tank Nut]

M5 High Speed tractor

A brilliant piece of engineering.  The thing could crawl or fly depending on how you operate it.  It'll pull a lot of weight and not overheat.  If you need to pull a 105 use an M5.

[sunday]

On the German side, perhaps the Famo. https://en.wikipedia.org/wiki/Sd.Kfz._9

[R011]

The "Quad" Field Artillery Tractors made by Morris, Chevrolet Canada, and Ford Canada, used to tow 25 pounders and 17 pounders, are kinda iconic.

[Argus]

AEC Matador, a 2-8-2 freight loco cunningly disguised as a 4x4 truck 

[DogDodger]

5 hours ago, Tim the Tank Nut said:

M5 High Speed tractor

A brilliant piece of engineering.  The thing could crawl or fly depending on how you operate it.  It'll pull a lot of weight and not overheat.  If you need to pull a 105 use an M5.

Driving it certainly sounded interesting: "The service clutch pedal was used to disengage the clutch and to select high or low clutch range. To change the clutch range, the pedal was pushed through the spring-loaded stop normally used to disengage the clutch and all the way to the floor. When the clutch was then fully released, it would be in the opposite range as before. The tractor was to be placed in motion using the clutch's low range, and could be switched to high range once ~2,500rpm was reached, after which rpm would drop to ~1,500. Changing from the clutch's high to low ranges required the engine to be at ~1,500 rpm, and after the change rpm would increase to ~2,500. Lights on the driver's instrument panel indicated which clutch range was currently being used. Shifting the transmission speeds required double-clutching, and each transmission speed was accompanied with shifting the clutch range, depending on if the tractor was accelerating or decelerating." Add to that a trailer brake pedal or button on the right steering lever, and the driver must have been dancing at times.

[futon]

The evolution of prime movers seem to go towards, (1) fast (over 40 kmph), (2) fully tracked, and (3) capable of carrying the gun crew. Those points look to be reached in the M5 High Speed Tractor with its development finished in mid 1942 and entering units in, I guess, later half of 1943. 

Did the British look into tracked prime movers for medium caliber guns?

Edited November 13, 2024 by futon

[Stuart Galbraith]

3 hours ago, futon said:

The evolution of prime movers seem to go towards, (1) fast (over 40 kmph), (2) fully tracked, and (3) capable of carrying the gun crew. Those points look to be reached in the M5 High Speed Tractor with its development finished in mid 1942 and entering units in, I guess, later half of 1943. 

Did the British look into tracked prime movers for medium caliber guns?

We used them for antitank guns. See 'Lloyd' and  postwar 'Oxford Carrier', which was often found towing the 6 pounder and I think 17pdr antitank guns.

https://en.wikipedia.org/wiki/Loyd_Carrier#/media/File:The_British_Army_in_North-west_Europe_1944-45_B11262.jpg

I think we viewed that if you had a tracked chassis, you may as well place the gun on them. If it was too big for the chassis, then get a truck to haul it. It seemed to work out ok.

My grandfather drove a 25 pounder Quad all through Sicily and Italy I gather. Morris Commercial one I think.

 

 

[futon]

44 minutes ago, Stuart Galbraith said:

We used them for antitank guns. See 'Lloyd' and  postwar 'Oxford Carrier', which was often found towing the 6 pounder and I think 17pdr antitank guns.

https://en.wikipedia.org/wiki/Loyd_Carrier#/media/File:The_British_Army_in_North-west_Europe_1944-45_B11262.jpg

I think we viewed that if you had a tracked chassis, you may as well place the gun on them. If it was too big for the chassis, then get a truck to haul it. It seemed to work out ok.

My grandfather drove a 25 pounder Quad all through Sicily and Italy I gather. Morris Commercial one I think.

 

 

Oh dang, you don't say, ok, I see. 

[Tim the Tank Nut]

it sounds way worse than it is.  Once you get used to it the process becomes very intuitive.  The pedals are relatively light so it isn't fatiguing.  The leverage on the steering levers is very good and the effort needed to affect a turn is relatively minimal.  The driver is in the center of the vehicle and up high so visibility is good.  The seat itself is wide and comfortable.  It's much easier and less tiring  to drive than a 2 1/2 ton truck is.  One of the downsides is the square body really hurts rearward visibility.  You can't see what you are towing very well.  Fortunately there's room for a helper in the back if you have to reverse while towing a load.

As far as I know they all came on steel track so traction was excellent off road (except in ice).  The rear idler was steel so track wear was minimal and you could be aggressive  in a turn while pulling something heavy and not have to worry about the rear idler sheering. 

The front and rear access doors probably should've been different.  The chances to get hurt seems pretty high.  You had to really pay attention to crew location or some dip would be sitting there in the front with their legs out right by the track, sigh...

[Rick]

That W.W.2 German motorcycle/half-track thingy.

[Markus Becker]

That reminds me of something (incomplete) we saw in Warsaw this summer:

 

I think it was the heavy C7P tractor. Poland had a medium and a light one too.

[R011]

13 hours ago, Stuart Galbraith said:

We used them for antitank guns. See 'Lloyd' and  postwar 'Oxford Carrier', which was often found towing the 6 pounder and I think 17pdr antitank guns.

https://en.wikipedia.org/wiki/Loyd_Carrier#/media/File:The_British_Army_in_North-west_Europe_1944-45_B11262.jpg

I think we viewed that if you had a tracked chassis, you may as well place the gun on them. If it was too big for the chassis, then get a truck to haul it. It seemed to work out ok.

My grandfather drove a 25 pounder Quad all through Sicily and Italy I gather. Morris Commercial one I think.

 

 

Obsolescent tanks like Lee/Grant and Crusader were often repurposed into artillery tractors.

Post war Canadian Army used M135 and MLVW 2 1/2 Ton trucks as 105 mm M101 tow vehicles and M39 5 Ton trucks as 155 mm M114 tow vehicles.  I also saw Chevrolet ! !/4 Tons used to tow L5 howitzers.  

[Stuart Galbraith]

10 hours ago, R011 said:

Obsolescent tanks like Lee/Grant and Crusader were often repurposed into artillery tractors.

Post war Canadian Army used M135 and MLVW 2 1/2 Ton trucks as 105 mm M101 tow vehicles and M39 5 Ton trucks as 155 mm M114 tow vehicles.  I also saw Chevrolet ! !/4 Tons used to tow L5 howitzers.  

Yeah, thats certainly true. I remember seeing a model of a conversion of an Airfix Crusader that was converted into a gun tractor. Thing is, I can never remember seeing a single photo of one in service, which suggests to me they were relatively uncommon. I do recall seeing a lot of AA conversions of Crusaders however.

There was also quite a few photos of Bishops, seems to have been a fairly popular conversion of Valentines when their main armament got too small.

[DogDodger]

On 11/14/2024 at 2:51 AM, Stuart Galbraith said:

Yeah, thats certainly true. I remember seeing a model of a conversion of an Airfix Crusader that was converted into a gun tractor. Thing is, I can never remember seeing a single photo of one in service, which suggests to me they were relatively uncommon. I do recall seeing a lot of AA conversions of Crusaders however.

There was also quite a few photos of Bishops, seems to have been a fairly popular conversion of Valentines when their main armament got too small.

I can't give any details of its service as this is currently 26th in line to read, but this may be an option if you're interested...

[Rick]

2 minutes ago, DogDodger said:

I can't give any details of its service as this is currently 26th in line to read, but this may be an option if you're interested...

Noticed you have "The Great Tank Scandal." Is that a good book?

[DogDodger]

5 hours ago, Rick said:

Noticed you have "The Great Tank Scandal." Is that a good book?

Some of Fletcher's assertions and views have been--at times pretty convincingly--debated over the past several years (e.g., Knight and the Covenanter tank). I'll still use it as a reference, but also won't feel too bad deferring to certain newer researchers. Note also that The Universal Tank is essentially the second volume of The Great Tank Scandal.

[Stuart Galbraith]

For me, I think Mechanised Force was the better book. If only because it supports the thesis that the MOD have been cocking up AFV design and procurement since the end of WW1.

 

[Ivanhoe]

Y'all are ignoring the equine prime movers of yore.

In most Hollywood movies, arty horses look pretty clean and mundane. The movie "War Horse", while kind of a dog's breakfast in terms of plot, showed what those poor horses had to deal with on the western front.

[Ivanhoe]

On 11/17/2024 at 3:00 AM, Stuart Galbraith said:

For me, I think Mechanised Force was the better book. If only because it supports the thesis that the MOD have been cocking up AFV design and procurement since the end of WW1.

 

Folks with a decent math background might observe that military design and procurement eff-ups are not just the transient solution, but the steady-state solution*.

* Obligatory George C. Scott reference; "Laplace, you magnificent bastard, I read your book!"

[17thfabn]

My Dad's unit used the M4 high speed tractor in the Korean War to pull 8" howitzers around. The M4 could also be used for moving the 155 mm gun (Long Tom).

[Argus]

On 12/2/2024 at 11:11 AM, 17thfabn said:

My Dad's unit used the M4 high speed tractor in the Korean War to pull 8" howitzers around. The M4 could also be used for moving the 155 mm gun (Long Tom).

The joys of modularity

[rmgill]

One of the nifty and I think smart details of the British gun tractors was often the fitting of a mid-ships winch to the truck allowing for the hawser to run via fairleads to the front OR back. This allowed using the cable and snatch blocks to get the guns to positions not otherwise easily done via manhandling. 

One of the other details is fitting lockers to the side of the bed for ammo and tools as well as an auxilliary cab behind the main cab for the crew to sit in for greater comfort rather than tossing them in the back with the ammo like US practice was. The locating of the ammo lockers on the side of the truck, accessible from the ground is also faster than shifting bulk ammo from the deep part of the bed AND also means the individual case are more secure. 

Generally you had something like this with 3, 4 or 6 seats arranged with space for rifles, tools and personal kit. 


In the range of this you have 
Bedford QLBs


You can see the stacy hitch for guns (basically leaf springs to cushion the towed load), the rear facing fairleads allowing direct to the rear or lateral left or right side pulls. There is likewise a fairlead to the front. 

On this desert tan QLB you can see the front mounted fairlead.
http://miliblog.co.uk/wp-content/gallery/british-ww2-trucks-medium/bedford-qlb-bofers-esk-412.jpg

The wheel scotches are for putting under the wheels and hooking via specific points on the frame and then driving ove them to have the wheels rest upon them, thus digging them into the ground and anchoring the vehicle. 

Some of the other winching kit are plates with loops in them for anchoring to the ground with long, 3' ling spikes (octagonal in section). 


Scammel Gun Tractors also had large midship whinces and were used for the heavier guns. Also note the aux cab but lack of side lockers due to the articulation of the rear wheel sets. 




The previously mentioned Quads/FATS from Chevy and Ford of Canada as well as Ford of UK and Morris. They had rear tool storage but ammo was stowed in the limbers. The basic org there was 4 guns per battery, 6 FATs (Field Artillery Tractors) and 8 limbers. 4 FATs tow a limber and a gun, 2 FATs tow two limbers. This allowed spare FATs AND the ability to keep a gun with a fully loaded limber AND shuttling the limbers back to supply to re-stock away from the gun. A nicely flexible system I think. 

The positioning of the limber NEXT to the gun enabled very fast servicing and minimal to-ing and fro-ing from the tractor. 



Here is a Cab 12 (Monkey faced) Chevy FAT. 



Rear view of a CMP FAT. Note again, stowage is easily accessed from on the ground around the truck. 


CAB 13 FATS were simplified with less modifications of the cab. 




Here's a Morris Commercial QUAD. 



And a slightly longer Morris Commercial C8 FAT.


There was also a C60X (6 wheel CMP) Tractor. I'm not sure how many of these were made. C60X's are kinda rare. 



Post War the British had the very heavy duty Leyland Martian 10 ton artillery tractors. 



Post war I know Canada has US built M35s of a number of flavors with modified cargo bed with ammo lockers accessible on the outside and with padded seats and greater crew comfort than the typical US M35A2 seating racks (which were basically oak slats and backs, which I am sure a number of members sorely don't miss). I'm sure Colin can give greater review of these as that was his area of operations. I can't at the moment remember what those are called to find a photo.  

Edited December 11, 2024 by rmgill

[rmgill]

On the 25 Pounder - Limber - FAT setup, they seem to be, for a 4wd truck, pretty capable off road all things considered. Obviously, reversing is a non starter, but the short wheel base allows a very tight turning circle. 
 

 

Edited December 11, 2024 by rmgill

[rmgill]

On 11/12/2024 at 5:48 PM, Argus said:

AEC Matador, a 2-8-2 freight loco cunningly disguised as a 4x4 truck 

Just about. That and the Scammells. Wood cabs....and all. Just not steam powered...


The Tractors differ from the cargo bodies in that you ahve an aux door in the cargo bed with a ladder, I think on both sides. Front mounted hitch for spotting guns. 


And midships winch with fairleads front and back for recovery (self, buddy and gun positioning). 



Here's a nice walk around of an AEC Matador Gun Tractor over on Flickr. 

These were for larger guns with Air brake systems it seems. The 8" BL guns and the like. You can see many of the details like the midship winch, the crew accomodations and other fiddly bits. 

Edited December 11, 2024 by rmgill