Practical Maintenance Guide for Elevators and Hoists: Safety Testing, Guide Rail Inspection and Traction Cable Examination

1. Scope and Purpose

This guide details essential preventive maintenance procedures to ensure the operational safety and reliability of industrial elevators and hoists. It covers the inspection and testing of safety devices, the evaluation of guide rails, and the comprehensive examination of traction cables. The execution of these tasks is critical to comply with UNE-EN 81-1/2 and AENOR safety regulations, prevent catastrophic failures and prolong the useful life of the equipment. This maintenance must be carried out according to the schedule established in section 8, or immediately upon any indication of anomaly or malfunction.

2. Safety Precautions

WARNING! Before starting any work, ensure that the equipment is completely de-energized and Lockout/Tagout. Handling elevators and forklifts involves serious risks of entrapment, falls and electrocution. Strictly follow your plant's procedures for controlling hazardous energy.
WARNING! Do not operate the lift or hoist if the safety devices are disabled or in bypass.
WARNING! Working at height requires the use of certified fall protection equipment (UNE-EN 361, UNE-EN 358). Ensure a secure anchor point.
WARNING! The traction cables may be under high tension. Avoid contact with moving parts and wear protective cut gloves (UNE-EN 388).

2.1 Personal Protective Equipment (PPE) Required:

• Safety helmet (UNE-EN 397)
• Safety glasses (UNE-EN 166)
• Work gloves resistant to cuts and abrasion (UNE-EN 388)
• Safety footwear with toe cap and anti-perforation sole (UNE-EN ISO 20345)
• Safety harness and lifeline (UNE-EN 361, UNE-EN 354)
• High visibility clothing

3. Tools and Materials Required

The following table details the essential tools and materials to carry out this maintenance task.

4. Pre-Maintenance Inspection Checklist

Perform this check before any major intervention to identify initial problems.

5. Step by Step Procedure

This procedure covers critical safety checks, guide rails and pull cables.

5.1. Equipment Preparation and Isolation

1. Verify work request and maintenance history.
   • Review records for previous repairs or recurring problems.
   • Common mistake: Ignoring crash history can lead to temporary fixes instead of permanent ones.
2. Go to the engine room.
   • Ensure access only to authorized personnel.
3. De-energize the elevator main supply.
   • Identify the main switch or disconnector.
   • Turn the main switch to the "OFF" position.
   • Check the absence of voltage with the multimeter at the output terminals of the main switch (230V AC or 400V AC, depending on the installation). The multimeter should read 0V.
   • WARNING! Always test the multimeter at a known voltage source before and after testing.
4. Aplicar el procedimiento de Bloqueo/Etiquetado (LOTO).
   • Colocar el dispositivo de bloqueo en el interruptor principal.
   • Attach the "DO NOT OPERATE" label with the technician's information and the date.
   • Common error: Skipping or performing an incomplete LOTO, putting personnel at risk.
5. Position the elevator car.
   • If possible, move the car to a position that facilitates access to the pit and the roof of the car (generally halfway). Use the engine room inspection selector if the equipment allows it.

5.2. Inspection of Safety Devices (Functional Tests)

1. Parachute Test (Speed Limiter).
   • In the engine room, manually activate the speed limiter lever, if the design allows, simulating overspeed.
   • Mueva la cabina en modo inspección a velocidad reducida (máx. 0.3 m/s).
   • Observe the activation of the parachute mechanism and the stop of the cabin. Verify that the cabin does not move more than 150 mm after activation.
   • Reset the parachute and speed limiter.
   • Common error: Failure to verify that the parachute reset is complete, preventing normal operation of the elevator.
2. Door Contact Test.
   • With the car on one floor and normal mode activated, try to manually open the car door while the elevator is stopped. The lift must not be able to start.
   • Try opening the landing door slightly. The elevator should not start.
   • Check the continuity of the door contacts with the multimeter. They must show open circuit (OFF) when opening and closed circuit (ON) when closing.
3. End Limit Switch Test.
   • With the cab in inspection mode, slowly move it toward the top end of the stroke.
   • Verify that the upper limit switch (UNE-EN 81-1/2 section 14.1.2) activates and stops the car before reaching the mechanical stops.
   • Repeat the process for the lower end.
   • Common error: Not respecting the activation clearances, which could lead to the car colliding with the stops. The activation distance must be at least 50 mm before the final stop.
4. Test the Emergency Alarm and Two-Way Communication.
   • From inside the cabin, press the alarm button.
   • Verify the audible activation of the alarm and communication with the control center or emergency personnel.
   • Ensure communication is clear and two-way.

5.3. Guide Rail Inspection

Inspection of the guide rails is crucial for smooth and safe travel of the cab and counterweight.

1. Visual inspection of the entire travel.
   • Use a strong flashlight and inspection mirror to examine the cab and counterweight guide rails along their entire vertical travel.
   • Look for signs of excessive wear, corrosion, warping, or impact damage.
   • Pay special attention to the rail joints.
2. Wear measurement.
   • Using the thickness gauge, measure the thickness of the working flange of the rails at several points along the route, especially in areas of frequent stopping.
   • Compare measurements to manufacturer's specifications. Wear greater than 10% of nominal thickness (e.g. if the 9mm rail is less than 8.1mm) requires attention.
   • Common error: Not detecting localized wear points, which can cause vibrations and accelerated wear of the pads.
3. Checking lubrication.
   • Check the presence of a thin, uniform layer of lubricant (ISO VG 220 grease or similar) on the contact surfaces of the guide rails.
   • Ensure grease fittings are clean and functional.
4. Check fixings and alignment.
   • Visually inspect and manually tighten the jaws and brackets for fixing the rails to the shaft structure.
   • Use the torque wrench to verify that the tightening torques are in accordance with the manufacturer's specifications (generally between 40 Nm and 60 Nm for M12 screws, UNE-EN ISO 4014 class 8.8).
   • Although alignment requires specific tools (laser), perform a visual check for verticality and parallelism. A visible misalignment generates vibrations.

5.4. Traction Cable Examination

The integrity of the traction cables is essential for safety.

1. Visual inspection complete.
   • With the cab in the pit (using the inspection control), visually inspect each pull rope along its entire accessible length.
   • Look for: broken wires, corrosion, deformations (bird cages, cracks, crushes), friction wear, loose strands.
   • Use the inspection mirror for hard-to-reach areas, especially around pulleys.
   • Common error: Not inspecting the critical flexing and contact areas with pulleys.
2. Count of broken wires.
   • According to the UNE-EN 81-1/2 standard, replacement of a cable is required if:
   • 6 broken wires in one twisting step.
   • 3 broken wires in a 30mm section of cable.
   • 1 broken wire in the anchoring or termination area.
   • Record the location and number of broken wires.
3. Measuring the diameter of the cable.
   • Use a vernier caliper or diameter gauge to measure the diameter of each cable at several points along its path.
   • Compare with the nominal diameter of the cable (marked on the cable itself or in the documentation). A diameter reduction greater than 10% (e.g. 10mm cable with 9mm or less) is a rejection criterion.
   • Ensure that the tension between cables is uniform. Use a cable tension meter (if available) to verify that the tension variation between cables does not exceed 5%. If there is no blood pressure monitor, a tactile evaluation (same deflection when pressing) can serve as an initial approach.
4. Inspection of cable connections.
   • Examine the wedges, bushings or anchoring terminals of the cables in the cabin, counterweight and traction pulley.
   • Look for signs of slipping, corrosion, cracks or damage.
   • Make sure the clips or clamps are properly positioned and tightened.
5. Cable lubrication.
   • Apply a specific lubricant for steel cables, following the manufacturer's recommendations. Lubrication protects against corrosion and reduces internal friction.
   • Common mistake: Using non-specific grease or oil that may attract dirt or not adequately penetrate the internal strands.

6. Post-Maintenance Verification Checklist

Confirm the correct operation and safety of the lift after the intervention.

7. Troubleshooting Guide

8. Recommended Maintenance Schedule

9. Spare Parts Reference

To ensure the availability and quality of components, consult the UNITEC-D GmbH e-catalogue.

For more information and spare parts availability, visit our e-catalog at https://www.unitecd.com/e-catalog/

10. References

• UNE-EN 81-1/2 Standard: Safety rules for the construction and installation of elevators. Part 1: Electric elevators. Part 2: Hydraulic elevators.
• UNE-EN Standard ISO 6789: Tightening tools for screws. Manual torque wrenches.
• UNE-EN 361 Standard: Personal protective equipment against falls from height. Anti-fall harnesses.
• UNE-EN 388 Standard: Protective gloves against mechanical risks.
• OEM documentation from the lift manufacturer (e.g. SCHNEIDER, KONE, OTIS, THYSSENKRUPP).