Eaton Corporation

Ian M Newbigging

David Edward Gibbons

A compound change-gear transmission (10) and control therefor are provided. The manually shifted compound transmission comprises a three-speed input splitter section (12) connected in series with a mulitple-speed, lever-shifted main transmission section (14) connected in series with a two-speed output range section (16). The input splitter section is controlled by a mulitple-position splitter selector switch (85), and the range section is controlled by a range switch which may be a manually operated device for repeat-I-type shifting (FIG. 4) or may be an autorange-type switch (86) for double-I-type shifting patterns.

Compound transmission with repeat or double-I shift pattern

A downshift control for a manually shifted transmission (10) is provided. The control senses vehicle ground speed (100) and compares same to predetermined maximum values (REF.sub.1, REF.sub.2) at which certain ratios are allowed to downshift engaged. If vehicle speed exceeds the reference (OS&gt;REF), a blocking plunger (216) assumes a position (216B, 216C) wherein selection of the prohibited ratio(s) is automatically mechanically blocked.

Downshift inhibitor

An automatic range shift control system for automatically controlling range section (14) shifting in an otherwise manually shifted range type compound transmission (10) is provided. A sensor (100) senses a value indicative of vehicle ground speed and provides a signal (100A) which is compared to a reference value. If the signal is greater than the reference, an actuator (96) is urged to engage the high speed range ratio and if the signal is less than the reference, the actuator is urged to engage the low speed range ratio.

Automatic range shift arrangement

A pneumatic control system for a range type compound transmission (10) is provided allowing preselection of a range section (14) shift by a range shift selector mechanism (98) and including an exhaust conduit control valve (118) which will prevent exhausting of one of the range actuator cylinder portions (120R, 120L) to atmosphere until the main transmission section (12) is shifted to a neutral condition.

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Bolton, United Kingdom

Ian M Newbigging