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Differential Steering

Started by Scott, March 06, 2003, 01:06:31 PM

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Scott

 I understand that hydrostatic steering (on a crawler) is controlled by hydraulics and allows for conterotations and as tight or loose of a turn as you want. My question is how does the differental steering compare to this in maneuverability and performance?

Mark M

Hi Scott

Maybe this will help:

Differential steering provides smooth, infinitely variable turning control with uninterrupted power to both tracks and excellent maneuverability in all applications. Differential steering allows easier turns while maintaining desired ground speed for fast cycle times and high production.

Mark

Scott

 Thanks Mark. Do you know why everyone else is runnung hydrostatic in thier dozers but Cat stuck with differential?

RMay

Scott the new cats are hydrostatic in the D-4 & D-5 they steer the same as J D- 450-650 . 8)
RMay in Okolona Arkansas  Sawing since 2001 with a 2012 Wood-Miser LT40HDSD35-RA  with Command Control and Accuset .

Mark M

Hi Scott

As far as I know of the track-type tractors only the D3G, D4G, and D5G have hydrostatic transmissions. The D5N and other models including the D11R have something called Finger Tip Control which combines the shift and steering into one control. This uses electric steering clutches and brakes and a programmable autoshift transmission. I am not very familiar with the transmission or steering on this unit but it sounds pretty neat. The medium and large tractors have powershift transmissions and torque dividers, and may or may not have differential steering. The torque divider transmission is a torque converter with a planetary gear set that multiplies engine torque. Depending on the load a portion of the power flow sthrough the converter and the other part is "divided" to direct drive. Under heavy load the most of the power flows through the fluid coupling of the converter. I think one of the biggest advantages of the hydrostatic transmission is counter rotation of the tracks of wheels that allows for greater maneuverability.

I think powershift is more efficient than hydrostatic and can transmit more HP, also there is a limit as to how much power the hydrostatics will handle. Pump and motor size would have to be very large to handle the HP of the large engines also there would be a hugh amount of heat that would have to be dealt with. Most if not all of the big Cat equipment uses mechanical transmissions, including the monster 797 truck. The hydraulic excavators of course use hydraulic track/wheel motors but all they do is move the machine, not much speed or load.

You can see what kind of power-train and steering the different machine have at
Cat Crawler Specs


Hope this helps

Mark

Scott


RMay

Mark we have three of the new D5 GLT and one of the JD-650 GLT at work . They replaced 20 to 30 year old JD 450 . We use them in wildland fire fighting . The cats and J.D. are like GMC and Chevrolet trucks almost the same . 8)
RMay in Okolona Arkansas  Sawing since 2001 with a 2012 Wood-Miser LT40HDSD35-RA  with Command Control and Accuset .

Mark M

Hi R

I'm not up on John Deere's product line any more. I know what a JD450 is though, I once rebuilt a transmission for one. I worked for a John Deere dealer in Int'l Falls for a while until they decided to close the branch. While I was there we mounted a delimber on the back fender of a JD skidder (540? can't remember). It worked pretty DanG good and was remote controlled. I wouldn't want to be setting in the cab when trees were going through that thing.

Cat's product line has changed so much that I have a hard time keeping up with it. I'm very familiar with everything up till about 1985 which is when I quit being a mechanic. Coming back after almost 10 years away and I feel lost.

Mark

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