起重机力矩限制器
Crane moment limiter
臂架起重机的工作幅度是一个重要参数。起重量与工作幅度的乘积为起重力矩。当起重量不变时，工作幅度越大力矩就越大。当起重力矩大于允许的极限力矩时，会造成臂架折弯或折断，甚至还会造成整机失稳而倾翻。根据起重机械安全规程规定：履带起重机、起重量≥16吨的汽车起重机和轮胎起重机、起重能力≥25吨的塔式起重机应设力矩限制器。力矩限制器的综合误差不能大于10%，应根据其性能和精确度进行调整或标定，当载荷力矩达到额定起重力矩时，能自动切断起升动力源，并发出禁止性报警信号。常用的起重力矩限制器有机械式和电子式。
The working range of jib crane is an important parameter. The product of lifting weight and working range is lifting moment. When the lifting weight remains unchanged, the greater the working range, the greater the moment. When the lifting moment is greater than the allowable limit moment, the boom will bend or break, and even cause the whole machine to lose stability and overturn. According to the safety regulations for cranes, moment limiters shall be installed for crawler cranes, truck cranes and tyre cranes with lifting capacity of more than 16 tons and tower cranes with lifting capacity of more than 25 tons. The comprehensive error of the moment limiter should not exceed 10%. It should be adjusted or calibrated according to its performance and accuracy. When the load moment reaches the rated starting gravity moment, it can automatically cut off the lifting power source and send a forbidden alarm signal. The commonly used lifting moment limiters are mechanical and electronic.
动壁式塔式起重机的超载保护装置用电子式力矩限制器。它一般由力矩检测器、工况选择器和微型计算机等组成。其工作原理是：当长度、角度检测器测出的臂长、角度值及工作信息经过数据采集电路进入计算机，计算出该工况的额定值，而力矩检测器测出的信号经过数据采集电路进入计算机，计算出实际值。将额定值与实际值进行比较，当实际值大于或等于额定值的90%时，发出警告信号；当实际值达到额定值时，发出禁止性报警信号，并通过自动停止回路，自动停止起重机向危险方向运动，但允许起重机向安全方向运动。同时，起重臂长的长度、角度、幅度、起重量等参数经软件程序中数字模型的计算，分别送到液晶显示器显示。
Electronic moment limiter is used for overload protection device of movable wall tower crane. It is generally composed of a moment detector, a condition selector and a microcomputer. Its working principle is that when the arm length, angle value and working information measured by the length and angle detector enter the computer through the data acquisition circuit, the rated value of the working condition is calculated, while the signal measured by the moment detector enters the computer through the data acquisition circuit and calculates the actual value. Comparing the rated value with the actual value, when the actual value is greater than or equal to 90% of the rated value, a warning signal is issued; when the actual value reaches the rated value, a prohibitive warning signal is issued, and the crane moves in dangerous direction is automatically stopped by automatically stopping the loop, but the crane is allowed to move in safe direction. At the same time, the length, angle, amplitude and lifting weight of the lifting arm are calculated by the digital model in the software program and sent to the LCD display separately.
小车变幅塔式起重机的超载保护装置，一般使用起重量限制器和起重力矩限制器来共同实施超载保护。起重量限制器是一个测力环，与起重钢丝绳导向滑轮刚性连接。测力环随载荷变化产生变形，并按设计程序通过不同的控制触电。起重量限制器有两个作用，一是当载荷达到某个值时，限制档位提升速度；二是当载荷达到最大值时，切断起升回路电源。设计原则是使起重机轻载高速，重载低速，超载停止。
The overload protection device of trolley luffing tower crane generally uses lifting weight limiter and lifting moment limiter to jointly implement overload protection. Lifting limiter is a force measuring ring which is rigidly connected with the guide pulley of the lifting wire rope. The force measuring ring deforms with the change of load, and electric shock is controlled by different design procedures. The lifting weight limiter has two functions: one is to limit the gear lifting speed when the load reaches a certain value; the other is to cut off the power supply of the lifting circuit when the load reaches the maximum value. The design principle is to make the crane light load high speed, heavy load low speed, overload stop.
桥架型起重机起重量限制器
Lifting Limiter of Bridge Crane
起重量限制器是起重机超载保护装置中最重要的部分，它主要用于桥架型起重机，一般由载荷传感器和二次仪表部分组成。传感器使用应变式或压磁式传感器。二次仪表由放大、比较、显示、控制等单元组成。现在，由于科技的发展使许多产品具有愈来愈多的附加功能，如大屏幕显示、计算打印等。
Lifting Limiter is the most important part of crane overload protection device. It is mainly used for bridge crane. It is generally composed of load sensor and secondary instrument. Sensors use strain or piezomagnetic sensors. The secondary instrument consists of amplification, comparison, display and control units. Nowadays, with the development of science and technology, many products have more and more additional functions, such as large screen display, computing and printing.
起重量限制器的安装形式有四种：吊钩式、钢丝绳式、轴承式和定滑轮式。
There are four installation forms of lifting limiter: hook type, wire rope type, bearing type and fixed pulley type.
1、吊钩式安装形式。吊钩式安装形式的产品结构，有直接显示式、调频发射式和分离式三种。直接显示式用于镍镉电池做电源，将吊钩、传感器、大屏幕显示器做成一体，装在起重机吊钩上。调频发射式也采用镍镉电池总电源，但没有显示部分，而是将传感器信号经调频后送司机室，由二次仪表把信号还原在进行控制与显示。这两种形式传感器与二次仪表之间不用电缆相连，但价格较高。分离式则将传感器信号经电缆传给二次仪表，经处理后进行控制与显示。
1. Hook type installation. The product structure of hook type installation includes direct display type, FM transmitting type and separate type. The direct display type is used for power supply of nickel cadmium batteries. The hook, sensor and large screen display are integrated and mounted on the crane hook. FM transmitter also uses the total power supply of nickel-cadmium batteries, but does not display the part. Instead, the sensor signal is sent to the driver's cab through FM, and the signal is restored by the secondary instrument for control and display. There is no cable connection between the two types of sensors and secondary instruments, but the price is higher. Separate type transmits the sensor signal to the secondary instrument through the cable, which is controlled and displayed after processing.
2、钢丝绳张力式。使用专用夹具，把传感器安装在起重钢丝绳，经过检测钢丝绳的张力来反映载荷。这种方式安装方便，检测精确度高。
2. Tension type of wire rope. Using special fixture, the sensor is installed in the lifting wire rope, and the load is reflected by detecting the tension of the wire rope. This method is easy to install and has high detection accuracy.
3、轴承座式。轴承座式安装形式的传感器采用双剪切梁式或圆柱形，配以专用附件，组成一个轴承座，安装在钢丝绳卷筒非减速器一侧。该形式装置方便，易于维修、精确度较高。
3. Bearing seat type. Bearing seat type sensor adopts double shear beam type or cylindrical type, with special accessories to form a bearing seat, which is installed on the non-reducer side of wire rope drum. The device is convenient, easy to maintain and has high accuracy.
4、定滑轮式。定滑轮式有两种具体安装形式。一种是配置一套托板支架，将定滑轮轴略微抬起，式安装在支架上的传感器承受载荷；另一种是支配定滑轮轴，把传感器压进轴的一端，安装时用这一根轴换掉原定滑轮轴即可。
4. Fixed pulley type. The fixed pulley type has two specific installation forms. One is to install a set of bracket bracket, which lifts the fixed pulley shaft slightly and loads the sensor mounted on the bracket; the other is to control the fixed pulley shaft and press the sensor into one end of the shaft, and replace the original pulley shaft with this shaft when installing.