Overload limiter of ship unloader (shore bridge)

Installation diagram of shore crane

IShip unloader overload limiter (shore bridge overload limiter）Overview
In the process of use, the shore crane needs to lift heavy objects of different tonnage, so it needs to be equipped with a set of automatic monitoring instruments to monitor the lifted objects in real time, judge the current working conditions, and make corresponding sound and light indications, such as normal lifting status, full load status and overload status
The overload limiter of our company's bridge erecting machine is designed for this type of crane, and is widely used in the safety protection device of the bridge erecting machine to ensure the safety of the crane and the operators. This product absorbs the advantages of the existing overload limiter in the market, and through the feedback of the lifting structure of the crane (weight sensor) to the instrument for collection, comparison, reading, judgment, display the current weight and indicate the corresponding working condition, After exceeding the rated weight, quickly cut off the lifting circuit of the crane hook, so that the crane can not lift heavy objects, so as to achieve the purpose of protecting the safety of the crane and operators. This series of devices has the characteristics of good performance, high reliability, light and convenient device

IIShip unloader overload limiter (shore bridge overload limiter）Configuration

IIIShip unloader overload limiter (shore bridge overload limiter）Configuration description
（1） Overload limiter host instrument
Ship unloaderOverload limiter(shore bridgeOverload limiter）Recommended instrument model: wtz-a (300)
Signal monitoring: 2-4 weight signals, equipped with 5 relays, which can meet the requirements of 5-clock status.
Screen display: large screen blue screen LCD display, and bar graph display of load rate percentage
Signal output: output relay signal or RS485 signal and 4-20mA
Installation method: wall mounted

Wtz-a (300) overload limiter instrument dimension drawing of wtz-a (300) overload limiter instrument
Ship crane overload limiter (shore bridge overload limiter）Other instrument models available for the host: wtz-a (100), wtz-a (400), wtz-a (150), wtz-a (230), wtz-a (240), wtz-a

Wtz-a100 overload limiter wtz-a400 overload limiter wtz-a150 overload limiter wtz-230 overload limiter wtz-a240 overload limiter wtz-a overload limiter

（2） Weight sensor
a. ZX type axial pin sensor
Installation position: installed in the lifting rope guide pulley
Installation method: replace the axle pin of the original bearing point
Force taking method: measure the pressure at the force point
Precautions: ① non standard sensors need to be customized
② The shear force of the force point and the sensor should always be consistent to ensure the output linearity of the sensor
Range selection: maximum force of current force point

Dimension diagram of ZX type axial pin sensor dimension table of ZX type axial pin sensor small range dimension diagram of ZX type axial pin sensor

ZX axis pin sensor ZX axis pin sensor is installed in Yangzhou Kejin Shipbuilding Co., Ltd

b. Py type side pressure sensor
Installation position: fixed end of wire rope
Power take-off mode: wire rope tension
Installation requirements: the lifting rope of the shore bridge must have a fixed end

Outline dimension drawing of Py type side pressure sensor


Py type side pressure sensor installation method of Py type side pressure sensor

c. BH-2 type plate ring pull sensor
Installation position: it is installed at the connection between the fixed rope (fixed rope) of the lifting rope and the lifting beam.
Power taking method: measure the tension of the lifting rope.
Precautions: ① the lifting rope must have a fixed rope (fixed rope)
② There is no fixed pulley at the connection between the fixed rope and the boom
Range selection: maximum rated lifting capacity ÷ wire rope magnification = sensor range

Outline dimension drawing of BH-2 plate ring pull sensor

BH-2 type plate ring pull sensor installation example of BH-2 type plate ring pull sensor

4、 Working principle of overload limiter
Overload limiter is composed of sensors, operational amplifiers, control actuators and load indicators. It integrates display, control and alarm functions. When the crane lifts an object, the sensor deforms, converts the load weight into an electric signal, and indicates the value of the load through calculation and amplification. When the load reaches 90% of the rated value, an early warning signal is sent; When the load exceeds the rated load, cut off the power source of the lifting mechanism. Overload limiter is widely used in bridge type cranes and lifts. Some jib type cranes (such as tower crane and portal crane) use overload limiter with torque limiter.

5、 Instructions for ordering overload limiter
1. Specific models (wtz-a100, wtz-a200 digital tube; wtz-a300, black and white screen or blue screen; wtz-a400, color screen machine, see product selection manual for details)
2. Please provide the rated weight, magnification and wire rope diameter of the bridge crane, and try to provide the load tonnage of the sensor when the crane is in the state of empty hook, and the load tonnage of the sensor when the crane is lifting the maximum lifting capacity, so that we can adjust the instrument to the most suitable working state of the crane during the production process
3. For different sensors, please provide detailed dimensions for our company to process kits.
Select bearing pedestal sensorPlease provide the dimensions of bearing pedestal base, including length, hole spacing, height, outer diameter, inner diameter and width of main shaft shell
Select pull sensorPlease provide the size of the steel wire rope sleeve or deformed ring, including the width, length and diameter of the shaft pin, whether it is a non-standard shaft pin (such as thin inside and thick outside). Generally, there is a lifting lug at the connection of the steel wire rope and the crane, and the width between the lifting lugs and the size of the shaft pin are required
4. Provide the cable length from the sensor to the driver's cab.
5. Please provide how many channels of weight signal control are required and how many types of control are required, such as overload (exceeding the rated weight), etc. which state (normally open or normally closed) the control relay needs to give

6、 Other
The shore crane can also be equipped with an anemometer. The anemometer is installed at the windward position of the gantry crane.