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Equipment Management Weekly Lesson (Belt Conveyor Backstop and its Maintenance Requirements)

2025-07-28 00:00

Overview of Backstops:
Backstops are safety devices used in conveying equipment to prevent reverse rotation due to the self-weight of the load after the equipment stops. Applicable to equipment requiring backstopping, such as belt conveyors, bucket elevators, and scraper elevators. Backstops are a type of special-purpose mechanical clutch, categorized into belt backstops, roller backstops, and wedge-type backstops. I. Contact Wedge-Type Backstop

A wedge-type overrunning clutch automatically engages or disengages with changes in speed or rotational direction. When used as an anti-reversal mechanism, it is also known as a wedge-type backstop or one-way bearing.
A wedge-type backstop mainly consists of an inner ring, outer ring, cam wedge, energy storage spring, sealing ring, and end cap. Contact wedge-type backstops are suitable for high torque, medium and high-speed transmission conditions. When used in high-speed conditions, they often use thin oil lubrication and special structures and materials for the wedges. Diagram of the internal structure of a contact wedge-type backstop II. Belt-Type Backstop During normal operation of the belt, the backstop belt is loose due to the movement of the return belt and does not affect belt operation; when the belt stops and reverses, the return belt drives the backstop belt to reverse into the space between the drive roller and the return belt until the backstop belt is fully extended, thus preventing the belt conveyor from reversing.

III. Roller Backstop
A roller backstop consists of a star wheel, rollers, and an outer ring. There are spring leaves or springs between the rollers and the blocks.

The star wheel is the active wheel and is connected to the reducer shaft. When it rotates clockwise, the rollers compress the spring due to friction and rotate with the star wheel. This is the normal operating state, and the inner ring of the backstop idles. When the belt reverses, that is, the star wheel rotates counterclockwise, the rollers roll towards the contracting part of the gap under the action of spring pressure and friction, wedging between the star wheel and the outer casing, thus producing the backstopping effect.
IV. Use and Maintenance of Backstops 1. The backstop should be installed only after the motor's direction of rotation has been determined. Installing it in the opposite direction can lead to serious malfunctions. 2. During installation, be sure to thoroughly remove burrs, clean, dry, and evenly apply lubricating oil. Avoid hard hammering and forced assembly. 3. The backstop should be lubricated with an appropriate amount of lubricating oil or No. 2 lithium-based grease. 4. The first oil change should be performed after the initial 100 hours of operation. In very dirty environments, a second oil change should be performed after 1000 hours. The oil change can be performed at the same time as the inspection of the transmission gears. 5. After two years of operation, the backstop should be disassembled, cleaned, and inspected. Bearings and wedge assemblies should have their grease replaced. The inspection should include checking for any loose or damaged springs, cracks in the wedges, inner ring, and outer ring, and whether the wedges swing and the bearings rotate smoothly. If any of the above defects are found, they should be replaced immediately. 擦力作用下滚移向空隙的收缩部分，楔紧在星轮和外套之间，这样就产生了逆止作用。

四、逆止器的使用和维护
1、逆止器的安装应在电动机的转向确定之后方可进行。如果安装方向相反，会导致严重故障。 2、安装中要注意彻底清除毛刺、洗净、擦干并均匀涂上润滑用的机油，严禁硬敲和强行装配。 3、逆止器应采用适量的润滑油或 2 号锂基润滑脂进行润滑。 4、最初工作 100h 之后，就应该进行第一次换油。在非常脏的环境，应在 1000h 之后进行第二次换油，换油可与检查传动齿轮同时进行。5、逆止器工作二年后，应拆开清洗，检查和更换轴承和楔块装配的润滑脂，检查内容主要包括弹簧有无脱落及损坏，楔块、内圈和外圈有无裂纹，楔块的摆动及轴承的运转是否灵活等。若出现上述缺陷，应立即更换。

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