Talk:Cross-drive steering transmission

Hydraulic pump

Sounds to me like the list of components of a cross-drive system at the opening is listing the components of a later M1 Abrams style cross-drive, the hydrostatic type. Why should the list for "components of a cross-drive system" include "hydraulic pump" and "hydraulic motor" when for the original, unmodified cross-drive this was a single component, a torque convertor? This relationship isn't at all clear from the article either. I only figured as far as that because I know what a torque convertor is, what a hydrostaic drive is, how they both work, and can see no other meaning of the "hydraulic pump/motor" than someone's attempt to interpret a hyrdostatic drive. Although I thought a lot of hydrostatics were basically like torque convertors but without a stator disc, making them fluid couplings. While "hyrdaulic pump/motor" might be strictly accurate, I'm not sure it's the best way to describe it. Anyway, it could be a lot clearer, since it seems almost to be talking about three different things, and it's not clear of both torque coverters and hyrdrostatics are meant to be included under "hyrdraulic pump/motor" or not.

70.109.163.78 (talk) 04:37, 24 November 2018 (UTC)[reply]

As I understand it, it is a motor and takes the place of the centre differential in triple differential steering, providing the driver with a greater degree of control over the vehicles steering. The pump & motor's direction and speed will determine the direction of the vehicle, the motor sending one track the inverse of the drive going to the other, each side using an epicyclic differential to add or subtract it from the main drive from the gearbox output. This system also permits neutral turns when the main drive is stationary.

That was probably a really horrible explanation as conveying concepts clearly and unambiguously is sadly not a talent of mine. --Vometia (talk) 09:01, 1 May 2019 (UTC)[reply]

Edit: Since I'm entirely rubbish at explaining things, I'm nicking this handy picture from the differential steering page which illustrates what I was on about. The hydraulic pump/motor arrangement would connect to the steering input. --Vometia (talk) 09:06, 1 May 2019 (UTC)[reply]

Article Inaccuracies - This article on the "cross drive" system contains numerous errors of technical fact, explanation and historical context. Cross drives do not use the torque converter (hydro-kinetic) in the cross drive to provide a variable rotation ratio between left and right tracks for steering - it is in the primary drive line. Only the later 1100 series incorporate a hydro-static (pump and motor) unit to provide such infinitely variable steering drive. Allison were not the primary innovators in providing regenerative steering. Other systems - principly the early 1940's Merrit-Brown were the leaders in this. And so on.