Sundstrand Sauer Danfoss Series 40 DDC Controls

The direct displacement control is on either side of a series 40 M25, M35 or M44 pumps. It just gives it a nice even control. When the control shaft moves it causes movement in the swashplate, making the pumps displacement go in one direction then making it go in the other direction.
In some applications it will need to make allowances for non linear control input to slack of control sensitivity when in neutral. To reach the the proper control you may need to to dampen or use frictional force.
The neutral mode is not anything the factory sets nor internal neutral return mechanism. That would require that application to have made allowances for control linkage and neutral return functions.

If you need further help with this, please call us at 800-361-0068
sales@hydrostatic-transmission.com