Com-Central.net

the ability to have a fully tracked vehicle spin its hull while remaining stationary?
And is this accomplished by having 1 track going forward and the other
going in reverse?

Thanks
Kevin

We always referred to this as a "neutral steer" in vehicles so capable (not all tracked vehicle were).

'Neutral turn' is the UK version....

BTW some wheeled vehicles are capable of doing it as well...

It's called 'neutral steer' because normally it is done with the transmission in neutral.

- kmeyer

the ability to have a fully tracked vehicle spin its hull while remaining stationary?
And is this accomplished by having 1 track going forward and the other
going in reverse?

There are two methods of doing this. Vehicles with a clutch-brake steering system can lock one track and transfer all power to the other and thus pivot over the locked track. In WWII that would apply to tanks like the German Panzer III and IV and the Soviet T-34. It is crude and wastes a lot of energy but works - though probably best if the ground is hard.

The other way is by means of turning the tracks in opposite directions. This can be achieved with tanks that have a separate steering drive from the engine. This can be found in many different steering systems but is basically a drive that operates at a fixed speed independant of the propulsion gear choosen. When the steering mechanism is engaged, either by clutches or brakes, the steering drive counterrotates and slows down the speed of one track throught differential or epicyclic gears. As the speed difference between the propulsion shaft and the steering drive shaft is determined by the gear choosen, you get a different steering ratio for each propulsion gear - narrow turns in low gear, wider turns in high gear. When the propulsion gearbox is in neutral, the steering drives is still turning and if you engage it by engaging the steering mechanism - pulling the steering levers - the tracks will turn in opposite directions and the tank turn on the spot. Hence the term "neutral turn". As each track is actually driven, this takes up a lot less energy than pivoting over the braked track as explained above.
This applies to British tanks like the Cromwell and Churchill or German tanks like the Panther and Tiger I and II, even though the actual steerings systems used were different. The French Char B1 had a rather clever version of this system, where the steering drive was turning a hydraulic drive, allowing and infinite number of steering ratios. It was needed, because it was the only means by which the hull mounted 75mm gun could be aimed - by the driver!

I've been told that even today, where tanks are a lot more reliable than they were in WWII, tankers only use neutral turns if it cannot be avoided, particularily off-road as it is quite hard on the mechanical bits and can cause problems with the track. Dont know if that is generally the case?

If you go to the British Pathé homepage and find film ID no. 1976.03, there is a short sequence at the end with Panther "Cuckoo", captured by the British, doing, among other things, a neutral turn.

[edit:] Just stumbled on another sequence on the British Pathé homepage, showing an FT-17 first struggling to run over a road sign, then doing a partial turn over one braked track. Its ID no. 1918.23

Claus B

PS: British Pathé can be found at www.britishpathe.com/index.html

The little experience I had actually driving a tank was in an M48A1. Neutral steering was easy. You put the transmission in Netral and turned the steering wheel ( a sort of Sideways figure 8 shape) in the direction you wanted to turn. The M48 was fun to drive the transmission wasa 2 speed automatic (I always wondered if it was related to the old Chevy Powerglide) as you were driving and you wanted more power you slapped it into low range, when you wanted to make more speed you slapped it into high. That was back when I was in ROTC. Funny thing was I didn't have a drivers license yet (couldn't afford the insurance) but I could drive a tank.

- bsmart

The little experience I had actually driving a tank was in an M48A1. Neutral steering was easy. You put the transmission in Netral and turned the steering wheel ( a sort of Sideways figure 8 shape) in the direction you wanted to turn.

Perhaps too easy. I noticed that there were warnings about touching the steering levers in the Cromwell and Churchill handbooks when the engine was running and the tank in neutral. Accidentally pushing one of the levers would start the tank turning. Probably not the greatest thing if tightly parked in the motorpool or next to a wall.

Claus B

Neutral steering on hard surfaces (like concrete), it went without saying, was discouraged when unnecessary because it scrubbed a lot of rubber off the ol' track blocks thus shortening replacement intervals. Leaves a spectacular tell-tale patch too that you don't want to be called upon to explain if you're just goofing around.

Hi Everyone,
Discouraged yes, exactly for that reason too Doug. But when out and about it can be a useful and FUN function, just don't get too carried away in sand or mud or you'll shed a track. Too much will accumulate and will lift the road wheels away from the center guides and then your in trouble. It also will build up between the track and sprocket carrier and roll off, even with the cut outs in it.
Claus, those warnings were also in the M1's ,M551's and M60's. That's why most units make it a rule to have a driver stay in position when the engine is running. Too many times a T-bar has been bumped getting in or out causing the tank to move and if your lucky hit the adjacent tank, a bad day is when there's someone between them. I have grabbed quite a few young troops/LT's in my day preventing them from walking between tanks that are running. They usually are parked only a couple of feet apart in the motorpool.

Joe D

Thanks Joe & Doug. Always nice to get a real-world perspective

Claus B

Like Joe said, I can't recall ever leaving one of the vehicle's referenced with the engine running unattended without the driver in position.

We always called it "pivoting", to pivot

The TM 9-2350-230-12 (M551 Sheridan) Op and Org Maintenance Manual calls this maneuver PIVOT STEER and was limited to low range foward and both reverse ranges.