Vertical reciprocating conveyors (VRCs) are simple machines with few things to go wrong.
Both hydraulic and mechanical lifts can run for decades with little downtime. If your freight elevator or dumbwaiter stops working, chances are it is one of the common problems below.
Try to troubleshoot the simple things on your own or call 404.429.5896 for service.
Hydraulic Lift Troubleshooting
- Lift doesn’t raise or lower: Check that all e-stop buttons are pulled out. This is the most common problem. Also, make sure the cage “safety arm” is covering the proximity sensor. Lastly, make sure all limit switches are engaged when doors are shut.
- VRC turns on and makes noise but the lift doesn’t raise: Check the hydraulic fluid level. You may hear a slurping noise and see an oil leak. If the oil level is low, the pump will turn on but have no fluid to fill the cylinders with.
- Stuck between floors: Product on the lift may have snagged the SJW wire that runs to the safety arm on the cage. If wires are pulled out mid-cycle, a fuse may have burned out on the transformer. Sometimes even the transformer burns out. Before replacing a fuse, ensure there isn’t continuity between the transformer and ground. This way you will not burn out expensive fuses only to realize the transformer is bad.
Mechanical Lift Troubleshooting
- Lift doesn’t raise or lower: Again, the most common problem for any machine is an engaged e-stop. Pull them out, reset, and restart the system. Also make sure limit switches are engaged on each floor. At the bottom of the pit, check the two chain tension sensors. If a chain link breaks or stretches, the sensor will trip. Repair the chain and/or readjust the chain tension. Sometimes a seized up carriage wheel will wear out leaving the cage slightly unlevel. This can affect chain tension on both sides of the lift and trip the tension sensor.
- Electrical short: As the lift raises and lowers, it can snag on liquid conduit and SJW inside the cage. If shorted, you could have blown fuses and a burned out transformer. Check for continuity on fuses and look for snagged wiring where the lift stopped between floors.
- Tripped sensor: Control power has a break if any switch, sensor, interlock, or door is ajar. These sensors typically do not break. Instead, it is usually the mechanical part pushing or pulling on them that is not functioning properly. For example, old Autoquip door magnets break or weaken and prevent the door from engaging the limit switch.