New Traction Machine Prevents Traction Elevator From Insufficient Power

I will introduce the elevator traction force inspection process and common problems, and analyze the causes and hazards of insufficient elevator traction force. Based on the traction and braking issues commonly encountered in conventional elevator traction machines, we have proposed a new elevator traction mechanism and explained its structural components and operating principles. This new traction mechanism not only provides safety protection during elevator operation, but also effectively rescues people trapped in elevator malfunctions. It also effectively prevents elevator slippage caused by insufficient traction force.

When inspecting elevator traction, inspectors typically follow the requirements of Items 8.1, 8.9, 8.10, and 8.11 of Annex A of TSG T7001-2009, "Rules for Supervisory and Periodic Inspection of Elevators - Traction and Forced Drive Elevators," and conduct the following inspection items in the following order: 1) Balance coefficient test; 2) No-load traction inspection; 3) Upward braking traction inspection; 4) Downward braking traction inspection. Each inspection item must pass before proceeding to the next.

During the specific inspection, inspectors use standard weights to measure the balance coefficient. A balance coefficient of 0.40 to 0.50, or the manufacturer's design value, is considered satisfactory. During the no-load traction inspection, after the counterweight compresses the buffer, short-circuit the upper limit switch, limit switch, and buffer plunger reset switch, and continue operating the elevator upward at the inspection speed. If relative slip occurs between the traction sheave and the wire rope, preventing the unloaded car from rising, the elevator meets the requirements. During the upward braking traction inspection with the car unloaded, if the main switch is disconnected and the brakes apply normally, bringing the car to a complete stop, the elevator meets the requirements. If the brakes apply normally but relative slip occurs between the traction sheave and the wire rope, the elevator does not fully stop and the traction force is insufficient, thus failing to meet the requirements. During the downward braking traction inspection with the car loaded at 125% of the rated load, if the main switch is disconnected and the brakes apply normally, bringing the car to a complete stop, the elevator meets the requirements. If relative slip occurs between the traction sheave and the wire rope, the elevator does not fully stop and the traction force is insufficient, thus failing to meet the requirements.

Based on the above tests, inspectors can determine whether the elevator's traction meets the requirements. During routine inspections, we've found that the most common traction force tests are during the upward and downward braking conditions. This is primarily due to insufficient traction, which causes the wire rope and traction sheave to slip over a considerable distance when the brake is applied.

During normal elevator operation, wear between the traction sheave groove and the wire rope is common due to the need for traction. However, if the traction sheave groove is severely worn, the difference between the tension of each wire rope and the average value of all ropes will be too large, not only preventing the elevator from operating safely, comfortably, and smoothly, but also creating the risk of insufficient traction. Traction is a key technical parameter for elevators. Insufficient traction can lead to slippage and sliding, which can easily cause serious accidents such as car roof collisions, car bottoming out, and even occupant shearing.

Some elevator traction motor manufacturers on the market have inherent defects in their traction motors, resulting in unreliable braking. Long-term use of wire ropes can lead to wear and rust, and wear in the traction sheave grooves can also cause excessive deviation in wire rope tension. Excessive car renovations can also increase the weight on the traction sheave car side. All of these conditions can lead to insufficient traction and the risk of slippage between the traction sheave and wire rope.

To address various issues currently associated with elevator traction machines, particularly insufficient traction force and braking problems, the authors propose a new traction mechanism that differs from conventional elevator traction mechanisms.

The structural components of the new traction mechanism are shown in Figures 1 to 5. When the traction machine is operating, the traction shaft rotates, driving worm gear A. Worm gear A is connected to auxiliary motors A and B at both ends. During this operation, auxiliary motors A and B rotate synchronously, and worm gear A does not apply driving force to worm gear A. If the traction machine experiences an abnormal operation, auxiliary motor A activates, and worm gear A applies driving force to worm gear A, thus providing protection. If the traction machine fails to operate and the car is not level, a professional can activate auxiliary motor B to move the car to level ground, providing emergency assistance.

The ends of the hoisting ropes A and B are connected to the car and counterweight, respectively. The ends of the wire ropes A and B are connected to the car and counterweight, respectively. When the hoist is running, the car moves up and down the track under the tension of the hoisting ropes A and B. The counterweight and counterweight move in the opposite direction of the hoist's movement, balancing the weight of the car and reducing the load on the hoist.

Two bevel gears A are double-sided and mounted on the traction shaft on either side of the traction sheave. When the hoist is running, the two bevel gears A rotate simultaneously, meshing with the four bevel gears B. There are four drive rods, one end connected to the bevel gears B and the other to the worm gears B. Therefore, the four worm gears B drive the four worm gears B. There are four rotating shafts and four clamping gears, one end of which is connected to the worm gear B and the other end to the clamping gears. Therefore, the four clamping gears rotate simultaneously under the action of the rotating shafts.

As shown in Figure 4, traction rope C has clamping gears on both its upper and lower surfaces, forming a clamping mechanism. The two clamping gears rotate in opposite directions, simultaneously exerting force on traction rope C, increasing friction and reducing the risk of insufficient traction.

When the elevator gearless traction machine stops operating, worm gear B and worm B lock traction rope C, further enhancing elevator safety.

Compared to conventional traction mechanisms, this new traction mechanism offers the following advantages.

One end of the traction shaft is connected to a worm gear, and the ends of the worm gear are connected to two auxiliary motors, one for protection and one for rescue. When the traction machine is running, the two auxiliary motors operate synchronously with the worm gear, creating no resistance. When the traction machine speed exceeds 105% of the rated speed but does not reach the speed limiter, or is below 92% of the rated speed, the auxiliary motors activate and apply force to ensure safe and reliable elevator operation. In the event of an elevator malfunction and entrapment, the auxiliary motors can be used for rescue, providing an additional rescue option compared to conventional elevators.
The clamping mechanism features two upper and lower clamping gears that simultaneously apply force to the traction rope, reducing the required traction force between the traction sheave and the ropes. This prevents slippage between the traction sheave and the ropes due to insufficient traction force caused by excessive car load. When the car is parked at a level position, the clamping device can also be used to clamp the traction rope, acting as an additional brake to prevent the car from moving downward.

In this article, the authors proposed a new elevator traction mechanism to address the common problems of insufficient traction and braking in conventional elevator traction machines. By incorporating two auxiliary motors and a clamping mechanism, this new elevator traction mechanism not only provides protection during elevator operation, but also enables effective rescue in the event of an elevator malfunction and entrapment. It also increases the braking force of the car when the elevator stops, preventing slippage caused by insufficient traction and reducing elevator accidents. While this new elevator traction mechanism demonstrates innovation in many aspects, it still has shortcomings in controlling and preventing excessive traction. The authors will continue to conduct in-depth research and optimize the design to effectively mitigate the potential risks associated with excessive traction.