T-34 Diesel Engines VS Panthers Gasoline Engine?

[Y Ddraig Goch]

I have a lot of designations for diesel and petrol engines and some hp/rpm ratings for the Maybachs but thats about it. There is an engine section somewhere on Chris's site.

[Ome_Joop]

One more thing the diesel RPM are lower than gasoline engines.This means that the transmission can be smaller.

I know the Panther had a very compact gearbox/transmission for such a big tank/engine....but i do wonder when your engine runs lower RPM's there is a stronger force at work than when working at somewhat higher RPM's (lower RPM's means more vibrations wich results in heavier gearbox/transmission!)

[Uncle Joe]

Gearhead, am I right in assuming that your oil refining figures are based on gasoline right after refining? Do you know what is the octane rating of such gasoline? It is less than 50. In other words, no WW Two tank engine is able to use a fuel of that low octane rating. And, if you wish to increase the octane rating of that 44 litres of gasoline, you will have less fuel, but of higher octane rating. Again in other words, your figures are of zero value for our purposes. Only if we know how much 70-80 octane fuel we get from that crude oil, then the figs have some bearing. On the other hand, that diesel fuel needs no further refining to be able used by standard diesel engines. Besidfes, which difference is greater, 36 vs. 44 or 170 vs 250?

Some diesels don´t have glow plugs, they have a small gas flame heating located in the induction manifold (i.e. the flame heats incoming air).

Regarding gearboxes, the size depends on how much torque is transmitted thru it and how many gears you need with the latter depending on torque rise characteristics of the engine and the speed range required for the vehicle. Although a diesel has usually greater torque per hp, therefore requiring greater strength and thus either better materials and/or bigger sized gearing, say a 5 speed gearbox for diesels is smaller and much simpler than an 8 speed box for Maybach engines. Example based on Spielberger´s data.

BTW, some members should obviously read some basic books on the subject as there are some have been naive posts in this thread, to say the least.

[Gearhead1432]

I don't hapen to know what the octane of raw gasoline is, but even at this early stage in refinement you still have more of it than gas oil. Further more, gas oil must be "cracked" before you have a useable product, however, in gasoline it is almost raedy to use. After the gas oil has been "cracked" you get a byproduct called cracked gasoline that is then mixed with the raw gasoline and pureified in a process called washing. At this point I belive the octane of the fuel is 65-70.
Also, the octane of gasoline can be very easily changed after the fact by *adding* other chemicals to the fuel like Ethyl fluid.

I see no evidence to suggest that enhancing the octane of a given gasoline reduces the total yeild of the finished product.

Rob

[Alter Mann]

From Technical History of the JagdTiger, by Andrew Devey, the Germans did start a project to develop an air cooled, X configuration, 16 cylinder Diesel engine for heavy AFVs. It was to be designed and produced as a joint venture between Porsche and Simmering-Graz-Pauker of Vienna. The engine designation was either Sla 16 or Porsche Type 212. It was a 36.8 liter engine that developed 750 horsepower. Unfortunately, development didn't start until 1945. According to the book one engine was tested in a Tiger B and 'it gave promising results during field trials'. The main disadvantage was that the hull required extensive modification in order to install the engine. It was an OHV design and consumed 800 liters of fuel per 100km for planning purposes. This engine never went into series production.

(Devey's book is also the best reference I have found for the design of the Maybach HL230 P30 engine. It includes many pictures and specifications.)

As mentioned previously, for a heavy and relatively slow vehicle, torque is more important than horsepower. For instance, the AVDS 1790-2 series of engines that powered the M-60 series of US MCTs during the 1960s-70s and 80s. This engine was an air cooled, V-12, 1790 cubic inch, Diesel, with one turbocharger per cylinder bank. I believe that it was SOHC. It used an electrical starting system and had a manifold pre-heater for use in cold weather instead of 'glow-plugs'. It had a planning range of 300 miles for 385 gallons of fuel. I'm sorry, but I can't convert that for comparison right now. Oddly enough, it was also rated at 750 horsepower, but was used in a tank that weighed between 52 and 60 tons, depending on model. Rated speed was 32 mph, but my driver in Germany got one up to 42 mph once, on flat ground.

I tried that argument about borrowing Diesel fuel from the German Navy once. My friend, The Argus, immediately pointed out that the Diesel fuel that the Navy used was considerably different from the fuel required by a regular Diesel engine. In short, the Navy didn't, and doesn't, have any significant amount of Diesel fuel that can be used in land based engines.

A few notes, from personal experience, about using tanks powered by Diesels in cold weather. I spent the Winter of 1978 at Bergen Hohen with 'B' Kompanie of the Bundeswehr 153 Panzer Battalion. Bergen Hohen is near the Arctic Circle, I believe. Anyway, it was very cold there.

At the time, the Army did not use any significant amount of multi-weight oil. An M-60 used in hot weather might have 50 weight oil in the engine and 30 weight in the transmission. For the trip to Bergen Hohen we used 10 weight in both engine and transmission. Still, we sent a man down to the track park every two hours at night to start all of the engines and let them run for a few minutes. This is only practical when fuel is not a problem. Starting the engines in the morning was never a problem, and I don't think anyone ever had to use the manifold pre-heater. (As a comparison, my wife drives a vehicle that has a 6.2 liter GMC Diesel in it. Any time the vehicle has been sitting for a few hours, it is recommended that the 'glow plugs' be used. Of course the engine has more than 250,000 miles on it.)

At Bergen Hohen, we were dependent on the Germans for fuel, which was supplied in 20 liter cans. Our tanks were not designed to be refueled in this manner. We always used hoses and nozzles from fuel trucks. One of the first problems was getting the fuel into the hole. The German tanks were equipped with rubberized canvas funnels in folding aluminum frames that allowed for easy refuelling from cans. When we tried to use them, we found that there was not enough room between the turret and the fuel fillers to set the frame up properly, which caused a small kink in the canvas funnel. Diesel fuel would not flow through this kink, at all. At the same time, the Germans were using an additive in 20 liter cans, labled 'Benzine', at a ratio of one can of Benzine to four cans of Diesel fuel. The Benzine would run through the funnels into our fuel cells without problems, so we refuelled with straight Benzine for the whole trip. I'm not sure how long the engines lasted after more than a month of this treatment, but I don't think it was very long.

[Alter Mann]

Ooops, I forgot to mention the engines used in US tank retrievers during this period. The M-88 tank retriever used a Continental AVS-1790 engine. It was a gasoline engine with mechanically driven superchargers instead of turbo-chargers, but, was otherwise very similar to the AVDS-1790-2 in the tanks. It was also a two spark-plug per cylinder design. The M-88A1, which, I think, was fielded in the late 1970s, used the same engine as the tanks it supported.

To give you an indication of the power that an M-88 could produce, one night, during a training exercise at Fort Hood, Texas, I saw an M-88 with two M-60A1s in tow going up a hill on a tank trail. It wasn't moving very fast, but it was pulling at least 104 tons of tank along behind it just fine. The total load that the engine was moving was more than 150 tons.

One impressive thing about the M-88 was that it didn't have much of an exhaust system. When towing heavy loads they used both spark plugs and opened the sections of grill door where the exhaust outlets were. They could produce flames, like a blowtorch, that were more than four feet long.

The only time I was ever towed by an M-88, I didn't think to remove my plastic water cans from their mounting on the bustle rack. At the end of the tow the water cans had completely melted and run down onto the front slope of the tank. It took about a week of chisel work to remove most of the mess.

[WotS]

I know the Panther had a very compact gearbox/transmission for such a big tank/engine....but i do wonder when your engine runs lower RPM's there is a stronger force at work than when working at somewhat higher RPM's (lower RPM's means more vibrations wich results in heavier gearbox/transmission!)

Not quite!

Yes this is true u need stronger(bigger,heavier) gears for diesel gearbox but lets take it this way that :gearwheel spin at lower RPM.It means less vibration. The smaller gear spins at higer rpm. The weight means nothing. It is all in balancing!

In conclusion the T-34 gearbox is smaller although the gearwheels are bigger.It just dont need so much gears!

[dragos]

T-34-85 powerplant

Type: V-34 or V2-34M
Cylinders: 12 in V @ 60deg
Piston travel: left block - 180mm, right block - 186.7mm
Displacement: 38.88 liters
Compression ratio: 14-15
Cranckshaft rotation: clockwise
Cylinders working order: 1l-6rl-5l-2r-3l-4r-6l-1r-2l-5r-4l-3r
Horsepower: 500HP @ 1.800rpm
Torque: 220 kgf.m @ 1.200 rpm
Specific diesel fuel consumption: 180gr/HP/hour
Specific oil consumption: 10gr/HP/hour
Engine weight: 900kg

[dragos]

Gearbox demultiplication ratios:

1st gear: 5.57
2nd gear: 2.6
3rd gear: 1.855
4th gear: 1.215
5th gear: 0.756
Reverse gear: 4.95

[Uncle Joe]

Dragos, interesting info! It basically confirms my recollection that the engine had very favorable power/weight and good torque. Specific fuel consumption figure is a bit higher than given in German source which puts the minimum at 158 g/hp/h. Even assuming the 180 figure is correct, it enjoys massive advantage over Maybach´s sfc of approx. 250 g/hp/h.

BTW, what is the source of this info?

[Alter Mann]

I find it interesting that fifth gear in the T-34 was an overdrive. Does anyone know if the Germans used any gear ratios of less than 1:1 in their tank transmissions?

[cbo]

I find it interesting that fifth gear in the T-34 was an overdrive. Does anyone know if the Germans used any gear ratios of less than 1:1 in their tank transmissions?

In the Panther box, 6th was 0.90 and 7th was 0.69. 6th in the Panzer IV box was 1:1.

Claus B

[WotS]

I find it interesting that fifth gear in the T-34 was an overdrive. Does anyone know if the Germans used any gear ratios of less than 1:1 in their tank transmissions?

In the Panther box, 6th was 0.90 and 7th was 0.69. 6th in the Panzer IV box was 1:1.

Claus B

I wonder that were 6 and 7 gears used in real combat too or only in test field?

[The Argus]

I've got to admit this is the fist time I'd heard this too.

But overdrive makes sense, stratigic as opposed to tactical mobility. Both countries made little use of tank transporters AFAIK and stressed mobility, so long road marchs made overdrive well worth the effort in terms of fuel ecconomy.

shane

PS Glow plugs, maniforld heaters and compressed air starting systems are all a great improvment over the only diesel I've operated for any length of time. Hand crank and decompressor valve make for hot work on cold mornings.

[Gearhead1432]

Okay... so how much torque does the Maybach make? doesn anyone know?

The T34 38.88L V12 is at about 1600 lbs/ft, which sounds realistic for the 500hp rating, but for the displacment it is rather....inefficient.

Rob