US 4,196,917 AGranted

Hydraulic lock for the swingable tongue of a towed machine

AssigneeDeere & Company

InventorsJay E. Oakes, Wilbur M. Davis

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Abstract

A pull-type mobile harvesting machine includes a header supported on a main frame and an arch-like tongue swingably connected to the main frame and extending forward over the header for pivoting connection to a tractor. A double-acting hydraulic steering cylinder controlled from the tractor is connected between the frame and tongue for swinging the tongue relative to the frame while the machine is advancing so that the machine is displaced laterally selectively between a range of operating positions, offset relative to the tractor, and transport positions, generally immediately behind the tractor. A shut-off valve in one of the hydraulic lines to the cylinder makes it possible to trap oil in one side of the cylinder in any given condition of cylinder extension, thus locking the tongue in a given position relative to the frame and also preventing flow of oil to the cylinder so that inadvertent manipulation of a cylinder control valve at the tractor does not cause accidental swinging of the tongue and lateral displacement of the machine relative to the tractor.

Claims9

Dependent claims

In a mobile machine designed to be pulled over the ground by a tractor, the machine having a rearward perimeter and including a main frame supported above the ground on at least one transport wheel having a steering angle normally fixed in relation to the main frame and including a forward extending elongated tongue releasably and pivotally connected to the tractor, said tongue being pivotally connected to and swingable in relation to the main frame about a generally upright axis so as to displace the machine laterally in relation to the tractor as the machine is advanced over the ground, such displacement embracing a range of operating positions in which the machine is substantially offset to the side of the tractor and a range of transport positions in which the machine trails substantially rearward of the tractor, and the tractor including a hydraulic coupling connected to a hydraulic power source on the tractor and a control valve manipulatable to control the flow of hydraulic fluid between the source and the coupling, improved control means for the tongue comprising:

a hydraulic actuator having an inlet, mechanically connected between the tongue and the frame and operable to swing the tongue into a preselected position relative to the frame as the machine is advanced;
and
a shut-off valve having an inlet connected to the coupling and an outlet connected to the actuator inlet, selectively operable between an open condition and a closed condition in which the actuator inlet is respectively operatively connected to or disconnected from the coupling so that manipulation of the control valve is, respectively, effective in swinging the tongue relative to the frame or ineffective so that the preselected position is maintained.

Dependencies are inferred from the claim text.