1-3
电梯的曳引传动
Traction drive
1-3-1 曳引传动定义：此传动系统通过摩擦 来带动电梯垂直运行的传动形式。具体地说 就是曳引绳悬挂在曳引轮上,一端悬吊轿 厢，另一端悬吊对重,曳引轮转动时, 由钢 丝绳与曳引轮槽之间的摩擦产生曳引力驱动 轿厢作上下运行。见图1-1。
由于悬挂轿厢和对重的曳引绳与曳引轮绳槽 间有足够的摩擦力来克服任何位置上的轿厢 侧和对重侧曳引绳上的拉力差，因此保证了轿
厢和对重随着曳引轮的正转和反转，而不断地上升和下降。 As a drive mode, traction drive can make lift
movevertically by means of friction. To be specific, tractionrope is suspended on the traction sheave,one side of which issuspended with car, the other side of which is suspended with counterweight. When traction sheave is rotating, the friction between traction rope and groove will produce traction force to move car upwards and downwards. See fig1-1 With enough friction between traction rope for suspending car and counterweight and rope groove to offset the differential tension on the traction rope of car and counterweight, car and counterweight keep on moving upwards or downwards by means of clockwise and counterclockwise rotation of traction sheave.
1-3-2 曳引传动的特点： Characteristic of traction drive
1-3-2-1安全可靠 Safe and reliable
当轿厢或对重因为某种原因超过了规定的行程碰到缓冲器时，曳引传动机构能自动消失曳 引能力，不至于继续曳引轿厢或对重而发生撞顶或墩底或拉断钢丝绳。
In case of car or counterweight runby to touch buffer, traction machine will lose traction capacity automatically, to prevent car or counterweight from colliding with top or bottom,
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or breaking traction rope.
1-3-2-2 允许提升高度大 High hoisting travel
曳引式电梯不像卷扬机那样，钢丝绳不断地一圈一圈地绕在卷筒上，其钢丝绳的长度不受 限制，因此可以实现将轿厢提升到任何实际需要的高度上。
Unlike windlass, traction lift can have ropes wound one by one around the coiler, with unlimited length, so as to hoist car to any desired height.
1-3-2-3 结构简单 Simple in structure
对于垂直起吊设备，根据规范要求，曳引轮（或卷筒）直径与钢丝绳直径之比不得小于40。 曳引式电梯可以比较容易地通过增加钢丝绳的根数或减少钢丝绳的直径，从而达到曳引轮 直径的减小和使整个机构的重量减轻。
To vertically hoist equipment, it is conventionally required that the diameter ratio of traction sheave (or coiler) to traction rope be ≥40. For traction lift, it is easier to decrease the diameter of traction machine and total weight by increasing rope number or decreasing diameter.
1-3-2-4 便于选用价格便宜、结构紧凑的高转速电动机。 Matching economical and compact high-speed motor
在电梯额定速度一定的情况下，曳引轮直径越小，则需要曳引轮转速越高，与此同时 也就要求驱动电动机转速越高。因此采用曳引式传动便于选用紧凑、价格便宜的高速 电动机。
If rated speed is definite, the smaller the diameter of traction sheave is, the faster the speed of the traction sheave and motor is required. Therefore, compact and economical high-speed motor can be used on traction drive.
1-3-3 常见的曳引传动形式 Typical traction drive modes
由于曳引机的位置、速度、负载等是不同的，钢丝绳的绕法也就不同，但要尽可能采用 简单的绕法和最少的定滑轮，以延长钢丝绳的寿命和提高效率。
Winding method for traction rope is different due to different position, speed and load.
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However, it is required to adopt simple winding and fixed pulleys as few as possible, to prolong traction rope life and improve efficiency.
1-3-3-1 钢丝绳绕绳方式 Traction rope winding method
曳引绳挂在曳引轮和导向轮上且曳引绳对曳引轮的最大包角不大于1800的绕绳方式称为单 绕，或称半绕；曳引绳绕曳引轮和导向轮一周后才被引向轿厢和对重的绕绳方式称为复绕， 或称全绕。复绕方式增加了曳引绳在曳引轮上的包角，提高了摩擦力。
Traction rope is suspended on traction sheave and diverter pulley; the maximum angle of traction rope to traction sheave should be ≤180°. Such winding method is defined as single winding or half winding. Traction rope will not lead to car and counterweight until it winds traction sheave and diverter pulley for one round. Such winding is called compound winding or full winding, which increases angle and friction.
图1-2-1为曳引机上置的钢丝绳绕绳方式，其中（A）、（B）、（C）为单绕方式，（D） 为复绕方式。Fig.1-2-1: Winding types for upper traction machine; (A), (B) and (C) are single winding, (D) is compound winding.图1-2-2为曳引机下置的钢丝绳绕绳方式，其 中（A）、（B）、（C）为单绕方式，（D）为复绕方式。Fig.1- 2-2: Winding methods for lower-placed traction machine; (A), (B) and (C) are single winding, (D) is compound winding.
1-3-3-2 曳引比 Traction ratio
曳引比是指电梯在运行时曳引钢丝绳的线速度与轿厢升降速度之间的比值。曳引比即为 绕绳比。若曳引绳的速度等于轿厢的升降速度，我们就称曳引比为1∶1，即曳引绳从轿 厢到对重，图1-2-1（A）的结构所示。若曳引绳的速度等于轿厢升降速度的2倍，就称 曳引比为2∶1，如图1-2-1（B）的结构所示。当曳引比为2∶1（如图1-2-1（B）所示）、 4∶1（如图1-2-1（C）所示）时，轿厢顶和对重上部都要安装动滑轮，每根曳引绳端头都 固定在机房上梁上，这样轿厢的速度分别为曳引绳速度的1/2和1/4，作用到曳引绳上的 载荷分别为1/2和1/4, 因而可减少绳直径或绳根数。
Traction ratio is defined as the ratio of lineal speed of traction rope to that of car running speed. Traction ratio is winding ratio. Given the speed of traction rope is equal to that of moving car, we call it 1:1 traction ratio, i.e. traction rope leads from car to counterweight,
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as shown in fig. 1-2-1 (A). Given the speed of traction rope is twice that of a moving car, we call it 2:1 traction ratio, as shown in fig. 1-2-1(B).
If traction ratio is 2:1 or 4:1, as shown in 1-2-1 (B) and 1-2-1-1(C), a movable pulley is required to be installed on the top of car and counterweight; traction rope head must be attached to the top of the machine room, therefore, car speed will be 1/2 and 1/4 of that of traction rope, and load on traction rope will be 1/2 and 1/4, making a reduction in rope diameter and number.
1-3-4 电梯的曳引能力 Traction capacity 1-3-4-1 曳引系数 Traction coefficient
电梯曳引绳受力简图如图1-3所示。设此时曳引绳在曳引轮上正处于将要打滑，
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