Importance

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Abstract

A powershift transmission having input, center and output clutch sections, each section including a plurality of clutches, is arranged to have a high and a low range of input/output speed ratios with some of the lower ratios of the high range being substantially equal to some of the higher ratios of the low range. During upshifting the shift sequence is 1L, 2L, . . . (N-2)L, (N-1)L, NL, 3H, 4H, . . . NH and during downshifting the sequence is NH, (N-1)H . . . 2H, 1H, (N-2)L . . . 2L, 1L wherein ratios (N-1)L and NL are substantially equal to 1H and 2H, respectively, L represents the low range, H represents the high range and N represents the number of gear ratios within each range. The arrangement avoids the need for simultaneous clutch swaps in all three clutch sections and reduces the number of shifts requiring simultaneous clutch swaps in the center and output clutch sections. This reduces the load placed on an engine during shifting because of the inertia of moving parts in the transmission, thereby providing smoother shifting particularly under heavy load conditions.

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First Claim