The present invention relates to a hydraulic cylinder systems of the heavy construction equipment equipped with a magnetic sensor attachment to sense the yarn exchange cycle, is mounted on the loading head 107 detects the operation of the stroke to be spaced above the magnetic 120 with a predetermined distance a hydraulic cylinder 100, a transmission unit for transmitting the received signal from the magnetic sensor 110 of the hydraulic cylinder 100 is provided with a magnet 120 that is attached to the magnetic sensor 110 and the cylinder head 108 for including 200 and a receiver 300 for receiving signals transmitted from the transmission unit 200, the reception unit 300, the transmission signal transmitted by the transmission antenna 240 of the transmission unit (200) and receive antenna 301 for reception, and the reception signal processing unit 302 for processing the transmitted signal received by the receiving antenna 301 to a reception signal, a signal processed by the reception signal processing unit 302 operation of the reception control unit 303 and the reception control unit 303 is received by the cylinder rod 103, the hydraulic cylinder 100, that it has reached the set number of times the stroke times of for delivery to the receiving MCU (304) characters to sound and the buzzer 305 and the LED (306) for transmitting the light emission, and the data counter 307 for counting a day using the count of the stroke of the hydraulic cylinder 100 by the control of the received MCU (304) , and the received MCU (304) cylinder operation counter 308 for counting a total use count of the stroke of the hydraulic cylinder 100 under the control of, a total counter for counting the chamber 111, exchange number 309 and , day counter reset switch 310, and a cylinder operating the counter reset switch 311 and the receive antenna 301, a reception signal processing section for resetting the cylinder operating the counter 308 to reset the day counter 307 302, the reception control unit 303, a buzzer (305) LED (306), data counter 307, a cylinder operation counter 308, a total of the counter 309, the day counter reset switch 310 and the cylinder operation counter is composed of a reception MCU (304) for controlling the operation of the reset switch 311, after the chamber 111 of the hydraulic cylinder 100 is exchanged, the cylinder operation counter reset switch 311 when the operation of the cylinder soon as the operation counter 308 is initialized to zero at the same time, characterized in that the total count display is configured of the counter 309 is counted up so that once.