Permissible minimum weight of car 当空载轿厢位于最高停站处上升制动时，

when car with empty load is decelerating towards the top landing,

当装有125%额定负载的电梯位于最低停站处下降制动时，

with 125% rated load, when the lift is decelerating towards the bottom landing,

从式1-5、1-6中可以看出，轿厢自重G越小则越接近e/C1C2，如果轿厢自重小到一定程度 则可能出现超过允许值e/C1C2的情况。在这种情况下，曳引绳就要在曳引轮绳槽上产生打 滑现象，因此我们必须限制轿厢最小自重。 设：电梯曳引比为k，

From formula 1-5 and 1-6, we can see that the smaller the weight of car ―G‖ is, the more it is approaching e/C1C2. If the weight of car is small enough, it is possible to exceed

fαfαfαefα/C1C2. Under such condition, slip of traction rope in traction rope groove will occur,

so the minimum weight of car must be limited.

电梯有补偿链或补偿绳装置时，式中P、k不存在。

If compensation chain or compensation rope device is available, P and k do not exist.

fαe? 1.5C1C2（2）当时

fαe? 1.5C1C2

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if

电梯有补偿链或补偿绳装置时，式中P、k不存在。

If compensation chain or compensation rope device is available, P and K do not exist.

1-3-4-5 提高电梯曳引能力的方法 Methods to increase traction capacity

从式3-2中可以看出提高曳引能力的途径，从大的方面说有两条，一是提高曳引系数e， 具体做法是增大摩擦系数f和增大包角α。二是降低比值T1/T2，具体做法是适当增加 轿厢自重，合理选择平衡链和平衡绳装置。

From formula 3-3, we can see there are two methods to increase traction capacity, one is to increase e，i.e. increase friction coefficient f and angle α; the other is to decrease T1/T2, i.e. appropriately increase car weight and adopt compensation chain and compensation rope device.

1-3-4-5-1 改变绳槽形状，增加摩擦系数

Change traction rope groove to increase friction coefficient

电梯是靠静摩擦力来传递动力的一种升降设备。摩擦力的大小，即摩擦系数的大小直接 影响电梯的曳引能力，因此正确选择曳引轮绳槽截面形状来提高电梯的曳引能力尤为重 要。在电梯上通常采用的曳引轮绳槽截面如图1-4所示。

Lift is a system which moves by means of static friction to pass dynamic. Friction magnitude, i.e. friction coefficient magnitude has a direct impact on traction capacity, so correct selection of traction sheave groove cross section plays a vital role in increasing traction capacity. Traction rope groove cross section is usually adopted as shown in fig.1- 4.

fαfα Page 26 of 40

由于曳引轮同钢丝绳的直径比受到限制，为了产生驱动力，交流电梯的曳引轮一般采用V 型槽。减少V型槽的角度，会使驱动力增加，但同时钢丝绳的磨损增加，槽形也发生变化， 影响驱动力以致发生钢丝绳打滑现象。

Since the ratio of diameter of traction sheave to that of traction rope is limited, to produce drive, V-groove is usually adopted for traction sheave of AC lift. Reduction of the angle of V-groove will increase drive, meanwhile, wear of traction rope is also caused, groove shape is altered, so that drive is affected, resulting in slip of traction rope. 半圆形槽较之V型槽据有较大的接触面，所以曳引绳与绳槽间所受的接触应力也较之V型 槽小的多。从钢丝绳和绳槽间的磨损方面看，半圆形槽比V形槽要小，但半圆形槽的摩擦 系数却比V形槽小的多。所以半圆形槽一般多应用于复绕结构中的曳引轮上和一般电梯的 抗绳、轿顶轮、对重轮上。

Compared with V-groove, semicircular groove has larger contact area, so the contact force between traction rope and traction sheave groove is larger than that of V-groove. Wear between traction rope and groove of semicircular groove is smaller than that of V groove, however, the friction coefficient of semicircular groove is much smaller than that of V groove. Therefore, semicircular groove is generally used in traction sheave with compound winding, counterweight rope, car top sheave and counterweight sheave.

半圆形带切口槽，介于上述两种槽形之间，即可以增大摩擦系数，提高曳引能力，也可以 使磨损降低，长期使用，摩擦力基本不发生变化。现在半圆形带切口槽已广泛用于电梯上。

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Semi groove with cut is between semicircular groove and V groove. It can increase friction coefficient and traction capacity, as well as reducing wear to prolong life since friction is presumably instant. Currently, semicircular groove with cut has been widely used in lifts.

1-3-4-5-2 增大包角 Increase angle

增大包角也可以提高电梯的曳引能力。

一是可以通过改变单绕式提升机构中的相关尺寸可以达到增大包角的目的。 二是采用复绕形式，这是增大包角最为显著的办法。

To improve traction capacity, we can increase angle by the either method:

Method 1: change relative dimensions in the single winding system to increase angle. Method 2: adopt compound winding to remarkably increase angle.

1-3-4-5-3 增加轿厢自重 Increase car weight

通过增加轿厢自重提高电梯曳引能力的实质是降低了T1/T2的比值。轿厢重量的增加会 造成材料上的浪费和价格的提高，因此在决定通过增加轿厢重量的办法来提高曳引能力 时一定要慎重。

Increasing car weight to improve traction capacity is in essence decreasing the ratio of T1/T2. Increasing car weight will aggravate material waste and cost, therefore, we should think twice before adopting such method.

1-3-4-5-4 合理地选择补偿链或补偿绳装置

Reasonably select compensation chain or compensation rope device

对于提升高度较大的电梯，曳引钢丝绳的重量不容忽视。如一台电梯的提升高度为60m， 用7根φ16mm钢丝绳，曳引比为1∶1。已知φ16mm的钢丝绳每米长0.9kg,则60m长度 的7根φ16mm钢丝绳重量等于378kg。

如果在电梯设计上能够把这部分重量平衡掉，则电梯的曳引能力就增加378kg。

设置补偿链或补偿绳装置，就是为了使电梯无论在什么为止，曳引钢丝绳自身的重量都不 要对曳引能力产生影响，其实质也就是降低了T1/T2的比值。当然设置补偿链或补偿绳也 有其减少电动机功率的作用。 电梯补偿链的位置见图1-5。

For lifts with long lifting travel, traction rope weight can not be ignored. For instance,

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