Abstract: A controller for controlling the slope of a screed supported by support arms wherein the screed is moved over a distance includes a first slope sensor which develops a first sensor signal representing the slope of the screed, a second slope sensor which develops a second sensor signal representing the slope of the support arms and a first summer which sums the first sensor signal and command signal indicative of a particular screed slope to develop a first error signal. An integrator integrates the error signal over distance to develop an integrated first error signal. A second summer sums the integrated first error signal with the second sensor signal to develop a second error signal which is utilized to control actuators which adjust the slope of the support arms.

Abstract: Machines having a boom or arm pivotally disposed thereon wherein the length of the boom or arm and the angle thereof with respect to a reference plane are adjustable by means of actuators are well known. However, it is extremely difficult, if not impossible, to simultaneously control the actuators in a coordinated fashion to move the end of the boom or arm in a straight line path. In order to overcome this problem, a boom control system for a boom according to the present invention controls the actuators in either of two modes of operation, the first mode of operation comprising independent control over each actuator to afford polar coordinate operation and the second mode of operation comprising synchronized control over the actuators so that the end of the member may be moved in a straight line. Means are provided for manually selecting one of the two modes of operation. Means may be provided for calculating the amount of remaining horizontal throw of the boom or arm when a command to move same is issued.

Abstract: An integrated hydrostatic transaxle having a common housing for a hydrostatic transmission and a pair of oppositely-extending differentially-connected axles to have the common housing provide a common sump therefor and with a specifically-shaped center section interconnecting the pair of hydraulic displacement units constituting the hydrostatic transmission. The center section is a unitary member separate from the common housing, with the exterior thereof exposed to the common sump. The center section has passages and arcuate ports which are interconnected by certain of said passages and which are located whereby the center section may be cast to minimize any machining required to finish the center section. Such casting can result in a porous center section with possible leakage from a passage having high pressure fluid.