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When the trolley rides as smoothly as possible across the bridge, and the bridge along the runways, you’ll enjoy more productive, dependable service from your overhead crane. Bridge and trolley bumpers designed to effectively absorb the damaging energy of impacts to promote safe, efficient operation and minimize equipment stress. Stops also play an important safety role, inhibiting trolleys from moving beyond the designed limit of travel. And rail sweeps, when placed on both ends of bridge trucks, help clear objects from runways that could damage or derail the wheels—not to mention your productivity.
This section further sets the standards for placement of guards. These include guards to protect personnel from moving parts, such as gears, chains and chain sprockets, and guards to keep hoisting ropes from touching bridge conductors or rubbing against other crane parts that will wear the ropes prematurely.
1. Stops shall be provided at the limits of travel of the trolley.( usually made of polyurethane.)
2. Stops shall be fastened to resist forces applied when contacted.
3. A stop engaging the tread of the wheel shall be of a height at least equal to the radius of the wheel.
A crane shall be provided with bumpers or other automatic means providing equivalent effect, unless the crane travels at a slow rate of speed and has a faster deceleration rate due to the use of sleeve bearings, or is not operated near the ends of bridge and trolley travel, or is restricted to a limited distance by the nature of the crane operation and there is no hazard of striking any object in this limited distance, or is used in similar operating conditions. The bumpers shall be capable of stopping the crane (not including the lifted load) at an average rate of deceleration not to exceed 3 ft/s/s when traveling in either direction at 20 percent of the rated load speed.
1. The bumpers shall have sufficient energy absorbing capacity to stop the crane when traveling at a speed of at least 40 percent of rated load speed.
2. The bumper shall be so mounted that there is not direct shear on bolts.
3. Bumpers shall be so designed and installed as to minimize parts falling from the crane in case of breakage.
1. A trolley shall be provided with bumpers or other automatic means of equivalent effect, unless the trolley travels at a slow rate of speed, or is not operated near the ends of bridge and trolley travel, or is restricted to a limited distance of the runway and there is no hazard of striking any object in this limited distance, or is used in similar operating conditions. The bumpers shall be capable of stopping the trolley (not including the lifted load) at an average rate of deceleration not to exceed 4.7 ft/s/s when traveling in either direction at one-third of the rated load speed.2. When more than one trolley is operated on the same bridge, each shall be equipped with bumpers or equivalent on their adjacent ends.3. Bumpers or equivalent shall be designed and installed to minimize parts falling from the trolley in case of age.
Bridge trucks shall be equipped with sweeps which extend below the top of the rail and project in front of the truck wheels.
Guards for hoisting ropes
1. If hoisting ropes run near enough to other parts to make fouling or chafing possible, guards shall be installed to prevent this condition.
2. A guard shall be provided to prevent contact between bridge conductors and hoisting ropes if they could come into contact.
Guards for moving parts
1. Exposed moving parts such as gears, set screws, projecting keys, chains, chain sprockets, and reciprocating components which might constitute a hazard under normal operating conditions shall be guarded.
2. Guards shall be securely fastened.
3. Each guard shall be capable of supporting without permanent distortion the weight of a 200-pound person unless the guard is located where it is impossible for a person to step on it.