Height control for implement support on an agricultural machine

Claim 2

An agricultural machine comprising: a vehicle displaceable along the ground and having a frame; an implement support pivotally mounted on said frame; a hydraulic ram connected between said support and said frame; sources of relatively high hydraulic pressure and of relatively low hydraulic pressure connectable to said ram; valve means between said sources and said ram for pressurizing said ram thereby lifting said support and for depressurizing said ram thereby lowering said support; first sensor means connectable to said valve means for operating same to maintain said support in a predetermined position relative to said frame; second sensor means connectable to said valve means for operating same to maintain said support in a predetermined position relative to the ground; control means connected to said valve means and to said first and second sensor means and having a single control element displaceable between a set position connecting said first sensor means to said valve means, a follow position connecting said second sensor means to said valve means, a raise position operating said valve means to pressurize said ram, and a lower position operating said valve means to depressurize said ram; and means for retaining said control element releasably in two of said positions and enabling free displacement of said element into and out of the other positions, said valve means having three positions: a lift position in which said ram is connected to said source of high pressure, a drop position in which said ram is connected to said source of low pressure, and a stop position in which said ram is disconnected from both of said sources, said control element having a fifth hold position corresponding to said stop position of said valve means, said control element being a lever having an end displaceable between a central position corresponding to said hold position and a plurality of other positions surrounding said central position and corresponding to the other positions of said control element, said means for retaining said control element releasably and lockingly securing same in only said hold, set, and follow positions, said element being nonlockingly received in said raise and lower positions.

Claim 3

The machine defined in claim 1 wherein said second sensor means includes: a vertically displaceable feeler engageable with the ground; and a pair of limit switches operable by and vertically flanking said feelers, said switches being connectable through said control means to said valve means and being positioned such that vertical displacement of said feeler by the ground above a predetermined level actuates one of said switches and below a lower predetermined level actuates the other switch.

Claim 4

The machine defined in claim 1 wherein said second sensor means includes a pressure-sensitive switch connected to said ram and having a first switch part operable when hydraulic pressure in said ram drops below a first level and a second switch part operable when hydraulic pressure in said ram rises above another higher pressure level, said switch parts being connectable through said control means to said valve means. 4. The machine defined in claim 3 wherein said second sensor means includes a pressure line connected between said pressure-sensitive switch and said ram and a restriction in said line limiting flow therethrough.

Claim 5

The machine defined in claim 1, further comprising pressure lines interconnecting said valve means, said ram, and said sources, and an accumulator connected to the line between said valve means and said ram.

Claim 6

The machine defined in claim 5, further comprising a pressure-relief valve connected between the line from said source of high pressure to said valve means and said source of low pressure.

Claim 7

An agricultural machine comprising: a vehicle displaceable along the ground and having a frame; an implement support pivotally mounted on said frame; a hydraulic ram connected between said support and said frame; sources of relatively high hydraulic pressure and of relatively low hydraulic pressure connectable to said ram; valve means between said sources and said ram for pressurizing said ram thereby lifting said support and for depressurizing said ram thereby lowering said support; first sensor means connectable to said valve means for operating same to maintain said support in a predetermined position relative to said frame; second sensor means connectable to said valve means for operating same to maintain said support in a predetermined position relative to the ground; control means connected to said valve means and to said first and second sensor means and having a single control element displaceable between a set position connecting said first sensor means to said valve means, a follow position connecting said second sensor means to said valve means, a raise position operating said valve means to pressurize said ram, and a lower position operating said valve means to depressurize said ram; and means for retaining said control element releasably in two of said positions and enabling free displacement of said element into and out of the other positions, said valve means having three positions: a lift position in which said ram is connected to said source of high pressure, a drop position in which said ram is connected to said source of low pressure, and a stop position in which said ram is disconnected from both of said sources, said control element having a fifth hold position corresponding to said stop position of said valve means, said control element being a lever having an end displaceable between a central position corresponding to said hold position and a plurality of other positions surrounding said central position and corresponding to the other positions of said control element, said means for retaining said control element releasably and lockingly securing same in only said hold, set, and follow positions, said element being nonlockingly received in said raise and lower positions, said first sensor means including: a pivot on said frame; a set-value indicator carried on said pivot; an actual-value indicator carried on said pivot adjacent and alignable with said set-value indicator; a link between said actual-value indicator and said support for coupling same together, whereby the angular position of said actual-value indicator on said pivot corresponds to the position of said support relative to said vehicle; means for positioning and holding said set-value indicator in a predetermined position; a pair of switches mounted on one of said indicators and engageable with the other indicator, said switches being connectable through said control means to said valve means and being positioned such that at least one of said switches is actuated by said other indicator when said indicators are out of alignment.

Claim 8

An agricultural machine comprising: a vehicle displaceable along the ground and having a frame; an implement support pivotally mounted on said frame; a hydraulic ram connected between said support and said frame; sources of relatively high hydraulic pressure and of relatively low hydraulic pressure connectable to said ram; valve means between said sources and said ram for pressurizing said ram thereby lifting said support and for depressurizing said ram thereby lowering said support; first sensor means connectable to said valve means for operating same to maintain said support in a predetermined position relative to said frame; second sensor means connectable to said valve means for operating same to maintain said support in a predetermined position relative to the ground; control means connected to said valve means and to said first and second sensor means and having a single control element displaceable between a set position connecting said first sensor means to said valve means, a follow position connecting said second sensor means to said valve means, a raise position operating said valve means to pressurize said ram, and a lower position operating said valve means to depressurize said ram; and means for retaining said control element releasably in two of said positions and enabling free displacement of said element into and out of the other positions, said valve means having three positions: a lift position in which said ram is connected to said source of high pressure, a drop position in which said ram is connected to said source of low pressure, and a stop position in which said ram is disconnected from both of said sources, said control element having a fifth hold position corresponding to said stop position of said valve means, said control element being a lever having an end displaceable between a central position corresponding to said hold position and a plurality of other positions surrounding said central position and corresponding to the other positions of said control element, said means for retaining said control element releasably and lockingly securing same in only said hold, set, and follow positions, said element being nonlockingly received in said raise and lower positions, said first sensor means including: a pivot on said frame; a set-value indicator carried on said pivot; an actual-value indicator carried on said pivot adjacent and alignable with said set-value indicator; a link between said actual-value indicator and said support for coupling same together, whereby the angular position of said actual-value indicator on said pivot corresponds to the position of said support relative to said vehicle; means for positioning and holding said set-value indicator in a predetermined position; a pair of switches mounted on one of said indicators and engageable with the other indicator, said switches being connectable through said control means to said valve means and being positioned such that at least one of said switches is actuated by said other indicator when said indicators are out of alignment.

Claim 9

The machine defined in claim 7 wherein said indicators are like semicircular disks and said switches are carried on the set-value indicator disk.

Claim 10

The machine defined in claim 7 wherein said first sensor means further comprises A height scale secured to said frame adjacent said set-point indicator, and pointers on said indicators alignable with said scale.