Mechanical transmission and controls therefor

#The present invention relates to a change speed transmission and controls therefor, and more particularly relates to improvements in transmissions and controls of the type disclosed in U.S. Pat. No. 2,710,546 which issued to DuShane and Rugen on June 14, 1955, U.S. Pat. No. 2,772,652 which issued to DuShane and Rugen on Dec. 4, 1956, and U.S. Pat. No. 2,839,941, which issued to Rugen on June 24, 1958. The transmission disclosed in the above-mentioned patents is particularly suited for use in tractors inasmuch as it provides a large number of forward and reverse speeds as is required for tractors. Specifically, the transmission disclosed in the above-mentioned patents will provide eight forward speeds and four reverse speeds although as a practical matter not all of the possible reverse speeds are utilized. The transmission controls disclosed in the above-mentioned patents provide a convenient way of conditioning the transmission for its different speeds or transfer ratios.

#While the speeds or transfer ratios of the transmission disclosed in the above-mentioned patents are adequate for the most common operations, some operations require additional transfer ratios so that slower speeds or more power transfer can be obtained. One simple and economical way to increase the speeds or transfer ratios obtainable from the transmission disclosed in the above-mentioned patents is to add an additional transmission section to the input thereof which would provide both a direct drive and an underdrive so that the number of speed ratios actually obtainable would be doubled. However, this would cause other problems inasmuch as the additional transmission section, when in the underdrive condition, could increase the torque to the basic transmission so that when the basic transmission is in the higher speeds damage would be very likely to result from overloading.

#The object of the present invention is to increase the number of speeds or transfer ratios obtainable from transmissions of the type disclosed in U.S. Pats. Nos. 2,710,546, 2,772,652 and 2,839,941 by providing a two speed or two transfer ratio transmission section in the input thereof and to provide an interlock between the controls of the two transmission sections which prevents the use of selected ones of the transfer ratios of the main section when the two transfer ratio section is in a selected one of its ratios, and to prevent use of the selected ratio of the two ratio transmission section when the main transmission section is in any one of its selected ratios.

#In the drawings:

#FIG. 1 is a longitudinal sectional view of a transmission constructed in accordance with the present inventions,

#FIG. 1A illustrating the input and forward portion of the transmission and

#Referring now to FIG. 1, there is shown therein a transmission indicated in its entirety by the numeral 10 and which includes a housing 12, the forward portion 14 of which is adapted to be connected to an engine block. The housing 12 includes a forward support wall 16, an intermediate support wall 18, and a rear or left end support wall 20. The support wall 16 and the engine to which the transmission is to be attached define a clutch housing, and a traction input shaft 22 extends axially within the clutch housing. The right end of the input shaft 22 is supported by bearing 24 located within a bushing 26 which is affixed within an opening extending axially into the end of an engine crankshaft shown partially at 28. The traction input shaft 22 extends through a hollow power-take-off (herein abbreviated as PTO) input driveshaft 30 and is journaled therein at its left end and intermediate its ends by bearings 32 and 34. The PTO input driveshaft extends through an opening provided in the support wall 16 and has its left end supported therein by bearing 36. The right end of the PTO input driveshaft is supported by the traction input shaft 22 through the bearing 34. The left end of the PTO input driveshaft 30 includes an integral gear 38 which is in constant mesh with a gear 40 fixed to a PTO shaft 42 having its right end supported by bearing 44 carried by the support wall 16 and an intermediate portion journaled in a bearing 46 carried by the support wall 20. A hydraulic brake piston 48 is axially shiftably mounted in the support wall 16 for selective braking engagement with an annular surface 50 formed on the gear 40.

#Located in the clutch housing is a dual clutch assembly indicated generally at 52 and including a traction clutch member 54 having a hub fixed for rotation with the traction input shaft 22 and a PTO clutch member 56 having a hub located axially adjacent the hub of the traction clutch member and fixed for rotation with the PTO input driveshaft 30. The hubs of the traction and PTO clutch members 54 and 56 carry annular, axially shiftable friction elements 58 and 60, respectively. A backing plate 62 of annular shape is located between the traction clutch and PTO clutch friction elements and is fixed to the rim of a flywheel 64 which is fixed to the engine crankshaft 28 by bolts 66. Pressure plates 68 and 70 are located on opposite sides of the traction and PTO clutch friction elements and, as is convenventional, are mounted for rotation with the flywheel 64 as well as for axial movement toward and away from the friction elements 58 and 60 to frictionally engage the latter with the backing plate 62.

#Actuating means for the traction and PTO clutches include annular, ring-like hydraulic pistons 72 and 74, respectively, which are mounted in the support wall 16 in concentric relationship to each other and to the driveshafts 22 and 30 and which engage the inner ends of sets of radially extending clutch operating fingers 76 and 78. When fluid pressure is applied to the left end of the piston 72 it shifts to the right against the inner ends of the clutch operating fingers 76 (only one of which is shown) to engage the traction clutch and establish a driving relationship between the engine crankshaft 28 and the traction input shaft 22. When fluid pressure is applied to the left end of the piston 74 it shifts to the right against the inner ends of the clutch operating fingers 78 (only one of which is shown) to engage the PTO clutch and establish a driving relationship between the engine crankshaft 28 and the PTO input shaft 30.