Saturday 24 August 2019

The American Highrise

Many Russian publications give the Medium Tank M3, known in the USSR as M3Sr (sredniy - medium) a poor evaluation. It is often dubbed "a grave for six brothers". Indeed, reviews of the M3 were the least favourable compared to most tanks that arrived in the USSR in large batches, but the infamy it holds today is not deserved. Let's try to objectively evaluate this American tank using reports from the proving range and the battlefield.

An overseas guest

The Red Army GABTU had more information about American medium tanks than light ones before the war. Significant amounts of information were obtained about the Medium Tank M2. Even more information was obtained in July of 1941, after which it was concluded that the Red Army has no interest in this tank. 

As for the main character of this story, the information on it was somewhat muddied. The Soviet military learned of the Ram I first, which was called "Canadian M-3" in correspondence. The description of a cast hull indicates that this was actually the Ram. This design, developed by British engineer Carr, was a characteristic of the Canadian vehicle. The M3A1 with a cast hull appeared much later.

Data on tanks that arrived in January-April 1942. The data is not entirely correct, as the numbers reflect only those tanks that arrived at the Gorky Tank Center, not all that arrived in the USSR.

As for the real Medium Tank M3, the USSR only learned about it in mid-September 1941. The source was the American press. The Heavy Tank T1 was discovered in the same way. Initially it was known as the "heavy 72 ton tank". Later the mass was corrected to 50 tons. The mass of American tanks was initially given in pounds, which the translators confused for kilograms. This resulted in an incorrect weight of 39 tons, which was quickly caught and corrected. By October of 1941 the Soviet military had enough information to decided to purchase tanks of this type.

Initially, the USSR made a deal for 9 tanks of this type. Only 4 came in December of 1941. Two were delivered to Murmansk and two more to Arkhangelsk. The delivery was recorded in January of 1942. 24 M3s arrived in January, after which delivery stopped for a month.

Another myth arose here, caused by incorrect descriptions in the documents. According to the myth the USSR allegedly received Medium Tanks M2A1 at first, which were sent to the 114th Tank Brigade. This is not the case. The registration numbers of all tanks that arrived in the USSR from January to April of 1942 are known. The numbers are not from the range assigned to the M2. The myth came to be due to the confusion between the Light Tank M3 and Light Tank M2A4. The latter was also never used by the Red Army.

Amtorg produced a manual for the American medium tank in February-March 1942.

The first issue experienced when running the M3 was fuel. As informed by General Faymonville, the M3's aircraft radial engine needed 91 octane gas. A solution was to use aircraft gasoline with the R-9 improver. B-78 gas needed 1 cubic centimeter of improver per liter, B-74 needed 2 cubic centimeters, and B-70 needed 3 cubic centimeters.

A lack of instruction manuals also caused problems. All that came with the tanks were a few brief booklets in English. Amtorg was tasked with urgently composing a manual in Russian. The manual was completed quickly, but there were a number of issues with it.

Placement of spare parts within the tank during its trip across the Atlantic.

Let us also mention the issue of shipments. Memoirs exist describing bottles of liquor and other presents from American workers hidden in the gun barrels. This did take place, but the military cared about ordinary equipment much more. Here is where the trouble began. Problems arose from the rapid increase in the volume of American production.

The issue of ammunition was the most critical. The first few shipments had no AP shells for the 75 mm gun. This led the GABTU to think that the 75 mm gun was meant for infantry support. The first AP ammunition arrived with PQ-14 in late April, only 1200 units. This was 40,800 short of the total amount needed to load up existing tanks.

The situation with HE ammunition was better. 153,694 rounds arrived by March 5th, but only 132,500 fuses. The situation with 37 mm rounds was also poor. 69,160 were delivered by May 10th with a need for 347,790. Recall that they were needed not only for the M3 medium, but also the M3 light. The lack of ammunition was one of the reasons why the combat debut of the American tanks came so late. Even though there were enough to equip two brigades by the end of March of 1942, the tanks went into battle only in May.

The tanks and spare parts often came separately. In June of 1942 15 tanks arrived with convoy PQ-15 without cupolas, which were sent separately. The same situation took place with 29 tanks that came with PQ-16. The issue was later resolved, but it cost the staff extra nerves. A proposal was made to weld the openings shut and send the tanks into battle as is.

29 tanks from PQ-16 also had faulty oil radiators. Deficiencies of internal components were also common, including the brass catchers and radios. The situation with pioneer tools was critical, and they had to be produced by Soviet factories. These issues were gradually ironed out, but the first half of 1942 was very tense.

Contents of the fighting compartment.

Despite all difficulties, supplies of the M3 ramped up in the spring of 1942. 44 arrived in March, 62 in April, 112 in May. The shipments peaked in June, when 121 tanks arrives. The infamous PQ-17 also carried M3 medium tanks, of which only 57 arrived at their destination. Shipments stopped for a month, but a new record was set in September: 256 units. In total 812 M3 medium tanks arrived in the USSR in 1942.

Unlike the M3 light, which arrived in large numbers through Iran, few M3 mediums came this way, only 26 in all of 1942. 117 tanks came in January of 1943, again mostly through the north. This was the end of mass shipments of the M3. Only 4 tanks arrived in February, 8 in April, 2 in May, and the last 2 in September.

945 M3 medium tanks arrived in the USSR officially, but in reality the number was higher. A transport with these tanks sank close to the Soviet shore in 1942. Twelve tanks were recovered and restored in 1943. They ended up in the 429th Independent Tank Battalion. Including these tanks, the total number of M3 mediums used by the Red Army was 957.

Big, roomy, hungry

Trials of the M3 were delayed. Tank U.S.A. W-304293 produced by the Detroit Arsenal was shipped to the NIBT proving grounds on February 18th, 1942, but trials began only on May 1st. The proving grounds in Kazan were busy with other issues at the time. The M3 light had to wait as well, and was tested in parallel with the medium tank.

M3 medium on trials, Kazan, May 1942.

The testers first remarked on the volume of the fighting compartment. The report indicated that 10 infantrymen with submachineguns could fit inside and the tank crew could still fire all weapons. The M3 was indeed a roomy tank. The loader of the 75 mm gun had the most free space, but the rest of the crew was packed into their corners. Later tanks lost their side hatches, so deploying these infantrymen would have been more difficult.

The same tank from the front. This was an early type.

The evaluation of the hull was predictable:
"The hull dimensions and layout are not modern.
The tank's excessive height and flat armour (aside from the front) create poor conditions for protection from enemy artillery"
The engine also received poor reviews. The trouble was not with reliability, but with the design and fuel required. The engine was too tall, which made the engine compartment large. Using 91 octane gasoline was also criticized. A diesel engine was preferred. In the spring of 1942 the GABTU requested the Medium Tank M3A1 with a Guiberson T-1400–2 engine, but the idea was discarded since the trials results were very mixed. As for the M3A3 and M3A5, these were not even considered in the USSR as the Medium Tank M4A2 was already known. That tank seemed far more interesting.

The design of the hull was not well liked. The tank was far too tall.

Unlike the engine, the transmission and cooling system were praised. The rubber coated track links were also deemed good, as was the VVSS suspension. However, the design of the return rollers was considered poor, as they quickly clogged up with mud.

The other edge of the sword was that the tank turned out to be very roomy, big enough to fit 10 infantrymen.

The 75 mm M2 sponson mounted gun received extra attention. In addition to the unusual placement of the gun, the periscopic sight proved interesting. The sight only had markings for AP shells, which the NIBT did not have at the time. The M24 sight used by the 37 mm gun had a lack of markings for HE as well, which did not endear it to the testers. There were also no markings for the machinegun.

The view from the back. The tank's components were hard to access, but their reliability compensated for that somewhat.

Despite the criticism of the sights and complaints about a lack of AP ammunition, the overall evaluation of the armament was satisfactory. The guns in the hull and turret were convenient to use. The same was said of ammunition racks. Only the fixed machineguns in the hull were criticized as they could not be aimed. The American military was not a fan of them either.

Visibility diagram from the tank.

Visibility from the tank was also studied. Soviet testers did not discover anything new in the design of the observation devices. According to them the observation was satisfactory. However, this "satisfactory" was far better than the T-34 and KV had.

Off-road trials, May 1942.

Mobility trials of the M3 were split into several stages. The first stage was brief, May 1st through 13th, 1942. The tank covered 285 km, 156 on a highway, 74 on a dirt road, and 55 off-road. The top speed of 34.1 kph was not impressive, considering the power to weight ratio of 14.8 hp/ton. To compare, the T-34 had 16.6 hp/ton and a top speed of 54 kph. The large difference was blamed on gear ratios. The average speed of the M3 on roads was 25.8 kph. The engine worked at 1500-2200 RPM. The average fuel consumption was 297 L per 100 km of highway dricing.

The tank would only get stuck in mud if it bottomed out.

The average speed on a dirt road was 17 kph, and 25-30 kph on certain flat portions. The fuel expenditure increased to 441 L per 100 km. The average speed off-road was 12 kph, but up to 18-20 kph on some parts. This cost 570 L of fuel per 100 km. The cruising range was 224 km on paved roads, 151 on dirt roads, and 117 km off-road. This was much better than the M3 light achieved in the same conditions. The tank demonstrated high off-road mobility. Even tough mud could be crossed as long as the depth of the mud did not exceed the tank's clearance.

The temperature of engine oil did not exceed 60-65 C during the trials.

The tracks slipped off when driving at a tilt.

Issues arose when driving on slopes and tilts. The rubberized T41 tracks were long lasting, but had bad traction. The flat bottom of the track links limited the tank's mobility. It could not drive up a 30 degree slope. The maximum tilt was 26 degrees, after which it began to slide and eventually the track would slip off.

Fording a river.

Trials continued in the summer. This time the program included fording a river and driving through a swamp. The tall engine compartment was a blessing here, as it was not flooded. As a result, the M3 could cross a ford where other tanks would stall. An issue arose when exiting the river, when the tank's engine deck tilted backwards, the engine took on water, and the tank stalled immediately. This problem did not occur on a more gently sloping shore.

The tank did not show itself well in a swamp. Its mobility was the worst of all the vehicles tested. After driving for 30 meters the tank bottomed out and became stuck. It could not free itself and had to be pulled out with a tractor.

The tank managed to cross slightly more than 30 meters of the 100 meter swamp course.

The initial program only included 1000 km of driving, but by the end of the summer the tank had driven for 1793 km: 332 on a highway, 1193 on a dirt road, 227 off-road. Few breakdowns occurred in this time. The electrical equipment was the least reliable: of 28 faults 13 had to do with it. Similar issues to the M3 light took place when the engine was started, which caused scorching of the exhaust pipes. One suspension spring broke. The reliability of the tank was considered high, and the time required to service it was low. However, it was remarked that the reliability was only achieved by correct and timely preventative maintenance. 

These drawbacks were not enough to call the American tank bad. However, sending it to units where domestic vehicles were being used was not recommended, as the difference in servicing methodology and type of fuel used was too great.

Driving in snow, winter 1943.

The tank took place in winter trials from January 21st to March 15th, 1943. The tank covered 1672 km, 248 on roads, 1059 on dirt roads, 365 off-road in the snow. Interestingly enough, the top speed in winter trials was 36 kph. The tank was tested both with grousers and without. The speed dropped noticeably with the grousers installed, but the off-road performance was higher. The fuel consumption increased as well. With 78 grousers installed the fuel expenditure increased to 582 L per 100 km on a highway an 965 L per 100 km off-road.

The rubber track links performed poorly in the winter.

The rubber track links worked worse during the winter than in the spring or summer. Even with six grousers per track, the maximum grade that could be climbed was 16 degrees. Installation of 78 grousers per side did not result in a large increase, only to 21 degrees. The greatest tilt at which the tank could drive in the snow was 16 degrees with 6 grousers and 22 degrees with 78.

Not all was bad. The maximum depth of snow banks that could be negotiated was 80 cm, same as the KV. The tank could drive through 30-50 cm deep snow in second gear. A snow clearing device was fashioned by the proving grounds staff and installed in front of the idler to clean the tracks.

Negotiating a snow barricade.

A 2 meter tall and 10 meter long snow barricade was constructed for these trials. The tank could penetrate it on the 6th try, a normal result for this type of tank.

Testers recommended using 6-8 grousers per track during regular travel and installing the full set only in very difficult terrain. The tank was deemed satisfactory in winter conditions, no worse than other imported tanks.

When it takes more than just machines

Foreign tanks in the Red Army were issued in such a way that each unit would have tanks built i one country. For instance, a tank brigade, battalion, or regiment with Valentine tanks would often also have Matildas. The same thing happened with American tanks. The 114th and 192nd Tank Brigades that were the first to receive the M3 medium used them alongside the M3 light. This made maintenance and supplies easier, especially for ammunition. The American medium tanks were often called "M3s" or "M3-S". 

M3 medium from the 192nd Tank Brigade, July 1942.

The opinion of American medium tanks was mixed from the start. The complaints were usually the same as those made at the proving grounds. On the other hand, the human factor must be considered. The testers said that the maintenance must follow instructions to the letter for a reason. This did not always happen on the front lines, and the result was a waning trust in the tank.

The first report arrived in late June of 1942 from the 114th Tank Brigade. It stated that the American M3 tank was fast, mobile, and quiet due to the rubberized track links. A speed of 30-35 kph could be maintained on the march. The armament was suitable for fighting tanks. However, there was no AP ammunition for the 75 mm M2 gun, and only HE was used. Theoretically, its penetration was about the same as that of the L-11 gun, which was sufficient for fighting tanks with 50 mm of armour at medium distances.

The drawbacks included small ammunition capacity (50 rounds) and a limited aiming arc. The tankers also did not like that the tank was large. This caused issues when digging in, and also the tank could not fire its 75 mm gun in this position. It was hard for tank riders to get on the tank. It also turned out that the 45 mm gun could penetrate the front of the M3 from 1000 meters. This resulted in deformation of the plates and bursting of the rivets, which made repairs impossible. Deformation of the hull also caused the observation devices to shatter and the hatches to jam.

The amount of porous rubber padding inside the tank was also a drawback. It often ignited when hit, poisoning the crew. The paint inside the tank would also burn. In these conditions fire and detonation of ammunition were common occurrences. The nickname "coffin for six brothers" (often there was no radio operator) was not given without reason. The order to remove the rubber lining wherever possible was given on June 30th, 1942, after the report was studied.

Another tank from the same brigade, captured by Germans.

Nevertheless, Malyshev's proposal to stop ordering M3 tanks was declined by the GABTU. The tank was effective in the right hands despite all of its drawbacks.

On May 23rd, elements of the 114th brigade crossed Severskiy Donets with the 242nd Rifle Division and 64th Tank Brigade and partially liberated the Chepel village. The village was fully cleared on May 25th. During this fighting the M3 tank commanded by Lieutenant A.D. Mimotin destroyed 4 German tanks. Another one destroyed 3 German tanks, but the crew died in the battle. The action at Chepel punched a breach in the German defenses and allowed several units to escape an encirclement. The brigade also excelled during the July battles against German counterattacks. According to Soviet reports up to 240 German tanks attacked on July 14th. The 2nd company of the 230th Tank Regiment commanded by Senior Lieutenant F.S. Glazkov (5 M3 light and 2 M3 medium) deflected 3 attacks, claiming 17 tanks. Of those, 4 burned and 2 disabled tanks were credited to the crew of Lieutenant N.D. Savva. Not bad for a "brothers' grave".

Several tanks were captured in running order.

The trail of the 192nd Tank Brigade was different. It ended up on the front lines in May of 1942, but sat idle for nearly two months. Large slogans appeared on the tanks during this time, which were made famous through photographs. 

These tankers fell victim to poor coordination with infantry. The Third Bolkhov Offensive Operation was a catastrophe for the brigade. At 5:30 am on July 5th, 1942, the brigade moved out with the 68th Tank Brigade to support the 149th Rifle Division. The Soviet infantry was suppressed by enemy fire and moved slowly. Tanks had to return for it several times, which led to additional losses. Colonel I.I. Petrov, the commander of the 192nd Tank Brigade, led a group of M3 light tanks into battle. The brigade political officers had to exit their tanks and rouse the infantry into following them. By 6:40 the strike group took Kabala and Bliznovskoye. The tanks pounded the German defenses, destroying strongholds. The artillery that was supposed to support the brigade with their fire lost their bearing. 6 tanks were lost to friendly fire.

The Germans counterattacked towards the end of the day, forcing the brigade back. More losses were taken from friendly fire. This time the 68th brigade confused the tanks for Germans. Several tanks became bogged down. Overall the brigade lost 40 tanks, some of which were captured by the Germans.

A tank that burned down in battle, 1942-43.

The sad story of the 192nd Tank Brigade echoed throughout the Eastern Front. For instance, the 92nd Tank Brigade from the 30th Army received an order to move out to Vernevo-Sevastyanovo on August 3rd. This was the start of the infamous Rzhev-Sychev operation. The brigade advanced until August 6th with mixed success until it reached Zubtsov. 4 M3 mediums and 6 M3 lights remained in action after just one day of battle.

The most unfortunate event took place in the fall of 1942 in the battle for Stalingrad. On September 26th, 1942, the 241st brigade with 24 M3 mediums and 27 M3 lights was attached to the 24th Army. The brigade was tasked with attacking alongside the 343rd Rifle Division towards the dairy farm and Noskin's Gulch. On September 30th the brigade broke away from their infantry, went over the ridge... and vanished. Only two tanks returned. As it turned out later, the German 3rd Motorized Division dug in at the dairy farm. 10 tanks were lost in a minefield, the others were lost to anti-tank guns.

The 167th Tank Brigade (32 Valentines, 21 T-70s) fell into the same trap. The Germans reported that 124 tank were knocked out. That wasn't it: the 38th Rifle Division and 114th Tank Brigade (30 M3 mediums and 16 M3 lights) was sent to help. They met the same fate on October 2nd. 4 tanks remained: 1 M3 medium in action and 3 M3 lights in repairs. It's hard to blame the tanks for this fiasco.

M3 medium in liberated Vyazma.

The M3 medium remained in use in 1943. The 245th Tank Regiment (12 M3 medium and 27 M3 light) fought at Kursk, on the south of the salient, subordinate to the 67th Rifle Division. It was in the way of the German strike group composed of 200 Panthers. Usually this battle is described as a slaughter of American tanks. It is true that the regiment took heavy losses during the first day, but they took their toll. The tankers reported 1 destroyed Tiger, 13 PzIIIs, 10 tanks, and 4 anti-tank guns. The tankers did not know that they were fighting Panthers. The documents describe firing on German tanks that crossed the anti-tank ditches and minefields with difficulty. The M3 lights excelled on July 5th, claiming 5 Panthers, but the mediums were no slouches either.

It is worth noting that tanks armed with the 75 mm M3 gun began arriving in the USSR starting in the second half of 1942. These guns had vertical stabilizers. The armour piercing rounds fired from this gun could pierce the side of a Tiger at a range of 400-600 meters, depending on the type of round. The T-34 could not pull off the same feat. It is hard to determine how many vehicles were knocked out for sure, but it is indisputable that a large portion of the German offensive fell victim to the 67th Rifle Division and 245th Tank Regiment.

One of the 12 "lost" M3 mediums from the 429th Tank Battalion.

The count of losses of M3 tanks looks interesting. As of January 1st, 1944, 676 out of 957 tanks of this type were lost. 281 remained operational. This seems like not that many, but if you compare it to analogous statistics for other foreign tanks, the ratio is about the same. The only exception would be Valentines and M4A2s, whose shipments continued. Ratios for tanks that were no longer delivered after the spring of 1943 are about equal. Few people call the Matilda a coffin on tracks, but its effectiveness was lower.

The condition of foreign tanks on July 1st, 1944, also looks interesting. 48 Matildas remained in the active army, 31 Churchills, 191 M3 lights, 143 M3 mediums (including the 12 tanks recovered from the sunken transport ship). While Matildas rarely showed up on the front lines and Churchills were confined north of Leningrad, American medium tanks were still encountered in ordinary tank brigades.

For instance, in July of 1944 there were 19 M3 mediums in the 41st Tank Brigade, which also had 32 T-34-85s and T-34s as of July 16th. The actions of the 5th Tank Corps in July of 1944 were reminiscent of the "heroism" of 1942. The first few days of the offensive were fortunate, but the fierce fighting for Malinovo began on the 22nd. The infantry did not support its tanks and the brigade took heavy losses. Losses were also suffered by the 48th Guards Heavy Tank Regiment that fought alongside the brigade. 5 IS-2 tanks were lost, and the regiment's commander was killed on July 23rd. By the 26th only 6 tanks remained out of the brigade, and by July 29th it counted only one T-34. Of the 29 M3 mediums 13 burned up and 6 were knocked out.

M3 medium on the march, summer 1944.

118 M3 mediums remained in action by January 1st, 1945, 16 of which were lost irreparably before the end of the war. Of the 102 tanks remaining by June 1st, 4 finished the war within the 1st Belorussian Front, 1 in the 2nd Belorussian Front, and 4 in the 3rd Belorussian Front. The M3 continued to fight until the very end of the Great Patriotic War. One M3 in the Transbaikal Front even managed to fight against Japan. The American tank was not that bad after all.

Only one tank survived to this day, the one that was tested in 1942-43. This tank can be seen on display in Patriot Park.


  1. Strange that a tank that was so ostracized managed to fight on all the way to 1945. I would of assumed they would of been used as driver training for M-4 Sherman tanks.

    1. Hey, it was definitely better than the "what even is HE lol" Brit infantry tanks and the crews weren't too fond of the tin-can SU-76 either. But they did the job so I rather imagine the brass were disinclined to pay much attention to such griping.

    2. Don't forget the Pacific, where the tanks that the Japanese fielded were more lightly armed and armoured, and the Lee's 37mm gun could provide canister shots to the infantry.

    3. Fair enough. The SU-76 was just a gun with a thin shield. And in the Pacific I believe the M-3s used tended to be those we shipped to India and Australia before production of M-4s got into full speed. And yes against the Japanese I bet the larger hull and the extra 37mm did come in handy.

    4. Even BT-7 and T-70 have seen end of the war far away from Soviet union. That does not mean much. To say SU-76 is just a gun with a thin shield is missing the point. Regardless of its thin shield, its strength was mobility. My understanding why M3 medium was disliked is not because it was terrible per say. It's because other tanks could do the job better and more efficiently.

    5. The impression I've gotten is that basically everyone liked the SU-76 very much... except the guys crewing them, as pulling frontline assault-gun duty with open top and barely bulletproof armour is obviously hazardous to both health and nerves.

      The M3 was probably in much the same situation (plus the usual "if you have them, use them" logic) - it was certainly useful enough but the people crewing the things would probably dearly have preferred being useful in something else instead...

    6. The SU-76 was hazardous when used as a tank because it was not a tank. If you're not going to push your ZIS-3 within 100 meters of the enemy by hand, you shouldn't do it with your SU-76 because that's not what it's for. The majority of SU-76 casualties came from unskilled combined arms commanders using them in precisely this way.

    7. Exactly Su-76 is basically artillery/anti tank gun under it's own power. And if used correctly as an support to tanks and infantry it proved more than adequate weapon. Reason why I stated mobility is its greatest strength is not because it's super mobile or fast. Its strategic and tactical mobility I was thinking about. It can come to where its needed and multiply the force to counter in defense or attack. More guns that are able to relatively quickly mass at certain points of the front the more chances of success.

  2. What a fascinating post. Are there any photos of the survivors at all? It would make a different scheme for sure.

  3. For speed I do wonder if the gearing was the problem or in reality just the engine's horsepower/RPM being limited.

    Unless I'm mistaken the gear ratios should be the same for all of the M3's and M4's.

    The Ram using the exact same engine/transmission was said to have a 48 kph top speed and a 40 kph cruising speed.

    The M4 (engine depending) can reliably get up to 48 kph for short periods.

    There's a few factors possibly at play. While the M3 and Ram and some M4's shared the same radial engine, they had it governed to a lower rpm then what the Ram had for example.

    Another possibility is earlier installations of the 975 engine had a few issues an example being the air cleaners which were located in the engine bay. This choked off the flow of clean air to the engine quite a bit, a field mod and eventually newer production vehicles would move these from inside and have them located outside the rear hull.

    This lead to an increase of an extra 72 horsepower measured at the propshaft after the switch. Quite a bit of lost power before that which would have influenced mobility.

    1. In my opinion gears ratio that's interesting case- I don't hear about different gears ratio in different Sherman tank engine version. I also don't hear about gear ratio differences in case of final drive and steering mechanism. But that's pretty strange for my- as example, typically passenger car with gasoline engine have different gears ratio in gearbox, than this same car with Diesel engine. From other hand, maybe this same gearbox in different Shermans mean smaller logistic problems.

    2. As far as I know with regards to gearing, I have only ever heard of different gearing being used in the M4A3E2 Sherman Jumbos - which had a lower final drive ratio to compensate for gained weight.

      The excellent Sherman tank site (www dot theshermantank dot com) shows the exact ratios involved - all Lee/Grant/Ram/Sherman chassis machines had the exact same gearing with the only exception being the lowered final drives on the Jumbo.

      Standardized gearing allowed dozens of small subcontractors to all contribute to drivetrain production but yes lead to some issues with engines that only liked to rev very high or very low.

    3. Final drive could ramain the same but it's not the only determining factor when it comes to speed. I couldn't find any information about transmissions for Canadian ram but it is different brand then M3. Original M3 had Mack and Canadian ram had Borg-warner. Weather they are identical or with slight difference remains mystery to me. Also I couldn't find any information about track length, are they identical? Few extra track links can change speed as it takes a bit longer for the track to travel full circle. Those are just some of the factors that can affect speed, carburetors are also a big variable even with identical engines, fine tuned carburetor can make a big difference.

    4. The Borg warner was the clutch a 3 disc design, eventually they all switched to the Lipe type a 2 disc design including the Ram.

      The suspension/track types and length are exactly the same on the Ram as the M4 other then stronger springs used in the original M3 type VVSS to better support it's heavier weight, they switched to the latter reinforced type VVSS when the M4 did.

      The Ram used a Mack truck designed Transmission as well made by Iowa transmission, at least for it's earliest Ram 1 models, that may have changed at later dates.

      Gear ratios are the exact same syncromesh design as on the M3/M4 afaik.

      1st gear 7.56:1
      2nd gear 3.11:1
      3rd gear 1.79:1
      4th gear 1.11:1
      5th gear .73:1
      reverse 3.64:1

    5. correction, reverse 5.65:1
      Bevel gear was 3.64:1

    6. Thank you for that information, very interesting stuff. If we deduct all those factors then the only variable is the engine and fuel quality that could make such difference.

  4. The engine output was related to the fuel quality it was made to run on. The lower the octane rating the lower the output. As this meant carb changes then swopping from one fuel type to another wasn't a two minute job. Certainly in the UK trucks running on pool petrol were like slugs compared to the same vehicles in assault formations running on higher rated stuff. My Uncle tells a tale of life driving a Queen Mary trailer with an old hand. His combo was about 5 mph faster than all the others, very handy when they reached the overnight point well ahead of the others....