Journal of Mechanical Science and Technology 30 (1) (2016) 211~220 www.springerlink.com/content/1738 -494x (Print)/1976 -3824(Online) DOI 10.1007/s 12206 -015-1225 -4 Configuration design of ten -speed aut omatic transmissions with twelve -link three -DOF Lepelletier gear mechanism† Essam L. Esmail* College of Engineering , University of Qadisiyah , Al Diwaniyah, Iraq (Manuscript Received September 2 , 201 4; Revised May 8 , 2015; Accepted September 22 , 201 5) ----------- ------- -------- ------- -------- ------- -------- ------- -------- -- ----------- ------- -------- ------- ----- --- ------- -------- ------- -------- -- ----------- ------- -------- ------- -------- ------- -------- ------- -------- -- ----------- ------- -------- ------- -------- ------- -------- ------- ---- Abstract Many Lepelletier -type automatic transmissions are in production. Some of Lepelletier related configurations are still far from reaching maximum possible sequential speed ratios. This work focuses on an alyzing and developing twelve -link three -DOF Lepelletier -type aut o- matic transmissions to attain maximum speed ratios. Following the general trend of increased shift stages and a wider range of speed ratios, new ten -speed automatic tr ansmissions are enumerated from the twelve -link three -DOF Lepelletier gear mechanisms. Furthermore, a ten -speed automatic transmission is modified from an existing eight -speed Lepelletier -type automatic transmission. The results show that the twelve -link t hree-DOF Lepelletier gear mechanism could reach eleven forward speeds at most. Nomographs are shown to be practical in detecting possible configurations and their clutching sequences. Keywords : Automatic transmission ; Clutching -sequences ; Eleven -speed; Planetary gear train; Gear ratios; Lepelletier ; Nomographs ; Ten -speed; Speed ratios ----------- ------- -------- ------- -------- ------- -------- ------- -------- -- ----------- ------- ---- ---- ------- -------- ------- -------- ---- --- -------- -- ----------- ------- -------- ------- -------- ------- -------- ------- -------- -- ----------- ------- -------- ------- -------- ------- -------- ------- ---- 1. Introduction Automatic transmissions with planetary gear trains have been used in the automotive industry for a long time. Famous compa nies have proposed several kinds of multi -speed aut o- matic transmissions. However, they always treat the develo p- ment of the automatic tran smissions as commercial secrets. Since research and development documents are mostly class i- fied, information can only b e obtained from patent doc uments, commercial catalogs, and non -academic magazines. The li t- erature on planetary gear trains includes kinematic analysis [1 - 5], dynamic analysis [6], power flow and eff iciency analysis [7-9], conceptual and co nfiguration desig ns [10 -21]. In 1992, Lepelletier [22] proposed three -DOF epicyclic gear mechanisms. These are now called Lepelletier gear mech a- nisms. In 2001, ZF used this gear set design to bring the first 6-speed passenger car transmission 6 HP 26 on the market [23]. The enumeration of clutching sequences has been the su b- ject of several academic studies for the past several years. The selection of an optimal clutching sequence cannot be solved analytically. Nadel et al. [24 -26] formulated the task as a co n- straint satisf action problem. Hsieh and Tsai [13, 15], Hwang and Huang [16] and Hsu and Huang [17, 18] used algorithmic techniques. Ross and Route [10] and Esmail [19] introduced graphic techniques. Hattori et al. [27] used phase geometry method. Refs . [10, 16, 26 -28] a re restricted to construc ting clutching sequences for specific types of automatic transmi s- sions. Hsieh and Tsai [15] used the concept of Fundamental gear entities (FGEs) proposed by Chatterjee and Tsai [12] in co n- junction with their earlier kinematic study [2] to determine the