【正文】 ractors and small lootives were built with frictiondisk transmissions with an output disk rolling on the face of the input disk. For disks of identical diameter, the effective gear ratio could be varied from 1:1 when the point of contact was at the perimeter of the input disk, to infinity when the point of contact was at the center, to 1:1 when the point of contact was at the opposite extreme. The transmission on early Plymouth lootives worked this way, while on tractors using friction disks, the range of reverse speeds was typically limited. The ratcheting IVT dates back to before the 1930s。 the original design converts rotary motion to oscillating motion and back to rotary motion using roller clutches. The stroke of the intermediate oscillations is adjustable, varying the output speed of the shaft. This original design is still manufactured today, and an example and animation of this IVT can be found here. Paul B. Pires created a more pact (radially symmetric) variation that employs a ratchet mechanism instead of roller clutches, so it doesn39。t have to rely on friction to drive the output. An article and sketch of this variation can be found here Many IVTs result from the bination of a CVT with a planetary gear system which enforces an IVT output shaft rotation speed which is equal to the difference between two other speeds within the IVT. This IVT configuration uses its CVT as a continuously variable regulator (CVR) of the rotation speed of any one of the three rotators of the planetary gear system (PGS). If two of the PGS rotator speeds are the input and output of the CVR, there is a setting of the CVR that results in the IVT output speed of zero. The maximum output/input ratio can be chosen from infinite practical possibilities through selection of additional input or output gear, pulley or sprocket sizes without affecting the zero output or the continuity of the whole system. The IVT is always engaged, even during its zero output adjustment. IVTs can in some implementations offer better efficiency in the preferred range of operation when pared to other CVTs because most of the power flows through the planetary gear system and not the controlling CVR. Torque transmission capability can also be increased. Staging power splits is also possible for further increase in efficiency, torque transmission capability and better maintenance of efficiency over a wide gear ratio range. An example of a true IVT is the Hydristor because the front unit connected to the engine can displace from zero to 27 cubic inches (440cm3) per revolution forward and zero to ?10 cubic inches (?160cm3) per revolution reverse. The rear unit is capable of zero to 75 cubic inches (1,230cm3) per revolution. However, whether this design enters production remains to be seen. Another example of a true IVT that has been put into recent production and which continues under mercial development is that of Torotrak. The ratcheting CVT is a transmission that relies on static friction and is based on a set of elements that successively bee engaged and then disengaged between the driving system and the driven system, often using oscillating or indexing motion in conjunction with oneway clutches or ratchets that rectify and sum only forward motion. The transmission ratio is adjusted by changing linkage geometry within the oscillating elements, so that the summed maximum linkage speed is adjusted, even when the average linkage speed remains constant. Power is transferred from input to output only when the clutch or ratchet is engaged, and therefore when it is locked into a static friction mode where the driving amp。 driven rotating surfaces momentarily rotate together without slippage. These CVTs can transfer substantial torque, because their static friction actually increases relative to torque throughput, so slippage is impossible in properly designed systems. Efficiency is generally high, because most of the dynamic friction is caused by very slight transitional clutch speed changes. The drawback to ratcheting CVTs is vibration caused by the successive transition in speed required to accelerate the element, which must supplant the previously operating and decelerating, power transmitting element. Ratcheting CVTs are distinguished from VDPs and rollerbased CVTs by being static frictionbased devices, as opposed to being dynamic frictionbased devices that waste significant energy through slippage of twisting surfaces. An example of a ratcheting CVT is one prototyped as a bicycle transmission protected under . Patent 5,516,132 in which strong pedalling torque causes this mechanism to react against the spring, moving the ring gear/chainwheel assembly toward a concentric, lower gear position. When the pedaling torque relaxes to lower levels, the transmission selfadjusts toward higher gears, acpanied by an increase in transmission vibration. roller The working principle of this CVT is similar to that of conventional oil pumps, but, instead of pumping oil, mon steel rollers are pressed. The motion transmission between rollers and rotors is assisted by an adapted traction fluid, which ensures the proper friction between the surfaces and slows down wearing thereof. Unlike other systems, the radial rollers do not show a tangential speed variation (delta) along the contact lines on the rotors. From this, a greater mechanical efficiency and working life are claimed. 附錄B：外文翻譯 這是最常見的CVT系統(tǒng),有兩個V型帶滑輪分別垂直的軸旋轉(zhuǎn),用三角皮帶傳動。通過移動兩組滑輪中的一個滑輪,靠近或者遠(yuǎn)離另一個滑輪來改變傳動比。V型帶的橫截面導(dǎo)致了兩個帶輪一個高一個低。這樣做改變了滑輪的有效直徑,進(jìn)而改變整個齒輪傳動比。滑輪的中心距并沒有改變, 皮帶的長度也沒有改變,所以齒輪傳動比變化意味著兩個滑輪都必須調(diào)整(一個大,一個小的)同時為了保持帶合適的張緊力。V帶需要緊密的包在帶輪上，以免出現(xiàn)徑向移動使V帶脫離帶輪。鋼制的三角帶是應(yīng)用于重量輕、轉(zhuǎn)矩小的多功能汽車和摩托雪橇。但是質(zhì)量高、轉(zhuǎn)矩大情況，比如：汽車，則需要鏈傳動。當(dāng)皮帶運行在最外層的半徑時鏈的每個鏈節(jié)都必須有有與滑輪相配合的錐形面。隨著鏈與滑輪接觸面積變小。因為接觸面積與鏈節(jié)數(shù)量成正比。因此，鏈輪需要許多非常小的鏈節(jié)。鏈節(jié)靜態(tài)的的形狀是圓柱。帶輪厚度由皮帶的最大傳動比和傳遞的最大轉(zhuǎn)矩之間所決定。同理，滑輪間的軸應(yīng)該盡量短一些。在一個鏈?zhǔn)綗o級變速器中在滑輪上形成油膜。它需要足夠?qū)捯员ＷC滑輪和鏈不接觸,又必須足夠短以保證不浪費能量（在潤滑良好的情況下）。此外,鏈節(jié)穩(wěn)定時大約是12節(jié)。每一節(jié)都很