1. Purpose and Purpose
This guide defines the operating procedures for the periodic maintenance of industrial lifts and hoists operating within production plants. The activities described are focused on safety-critical components: emergency stop devices (parachutes), slide guides and suspension wire ropes. The objective is to guarantee full compliance with the safety requirements established by current regulations, in particular UNI EN 81-20 and UNI EN 81-50, preventing sudden failures and guaranteeing maximum availability of the production system.
2. Safety Precautions
WARNING: RISK OF FALLING FROM A HEIGHT AND CRUSHING. Access to the lift shaft must occur exclusively after carrying out the LOCKOUT/TAGOUT (LOTO) procedure. The use of a complete safety harness anchored to certified points, helmet with chin strap, cut-proof gloves and S3 safety footwear is mandatory. Never attempt maintenance with the system running, except for specific tests that require operation at reduced speed. In such cases, operate exclusively from the inspection button panel on the cab roof with a second operator present and ready to intervene on the emergency stop command.
3. Tools and Materials Required
| Tool | Specify | Quantity |
|---|
| Torque wrench | Range 5-100 Nm | 1 |
| Digital caliper | Accuracy 0.01 mm | 1 |
| Laser alignment tool | Accuracy 0.1 mm/m | 1 |
| Rope tension meter | Calibrated for rope diameter | 1 |
| Magnifying glass | 10x magnification | 1 |
| Guide lubricant | Certified for industrial use (acid-free) | 1 bottle |
4. Pre-Maintenance Inspection Checklist
| Item | Check | Acceptance Criteria | Notes |
|---|
| Wire ropes | Wear, corrosion | No broken strands, diameter reduction < 5% | Check anchor points |
| Guides | Lubrication, alignment | No rust, uniform lubrication | Check sliding games |
| Parachute | Mechanical operation | Free movement of the jaws | Cleaning from dust accumulation |
| Speed limiter | Rope tension, rotation | Smooth rotation, no vibrations | Check safety switch |
5. Step-By-Step Procedure
5.1 Inspection and testing of wire ropes
- Position the cabin in inspection position. Electrically isolate the control panel.
- Clean the surface of the rope with a rag soaked in a specific solvent to remove surface grease and dirt.
- Visually examine the rope using the 10x loupe to identify broken wires (strands). Common mistake: ignoring the presence of internal corrosion; if in doubt, use ultrasound.
- Measure the diameter of the rope at three different points along the stretch of maximum stress.
- Check the tension of each individual rope. The tension difference between the ropes must not exceed 10%. Adjust the tension nuts if necessary, tightening to 30 Nm.
5.2 Inspection and adjustment of the guides
- Inspect the verticality of the guides using laser alignment over a 2 meter stretch. The maximum deviation allowed is 0.5 mm.
- Check the tightness of the fixing flanges to the compartment structure. Recommended tightening torque: 85 Nm.
- Wipe off any excess dirty lubricant and apply a thin layer of new lubricant. Common mistake: excessive lubrication which attracts dust and debris, increasing shoe wear.
- Check the clearance between the faces of the guide and the sliding brackets. The clearance should be between 1.0 mm and 2.0 mm on each side.
5.3 Testing the parachute device
- Make sure the system is at rest.
- Manually, activate the speed limiter to simulate the intervention.
- Check that the parachute jaws lock onto the guide with even pressure.
- Measure the footprint left on the guides. It must not exceed a depth of 0.2 mm.
- Reset the system following the OEM procedure (often requires lightly lifting the cab).
6. Post-Maintenance Verification Checklist
| Tests | Expected Result | Pass/Fail |
|---|
| Parachute operation | Immediate intervention at the test | [ ] |
| Rope tension | Difference between ropes < 10% | [ ] |
| Scrolling guides | Absence of noise/vibrations | [ ] |
| Electrical safety test | Immediate interruption | [ ] |
7. Troubleshooting Guide
| Symptom | Probable Cause | Corrective Action |
|---|
| Vibrations in the cabin | Misaligned or dry guides | Align guides and lubricate |
| Metallic noise | Loose or worn ropes | Repair or replace ropes |
| Parachute does not reset | Dirt residues | Clean and lubricate pins |
| Stopping not smooth | Shoe wear | Replace parachute jaws |
8. Recommended Maintenance Schedule
| Tasks | Frequency | Estimated duration | Skill Level |
|---|
| Rope inspection | Monthly | 1 hour | Basic technician |
| Guide lubrication | Quarterly | 2 hours | Expert technician |
| Parachute/limiter test | Semi-annually | 3 hours | Expert technician |
| Total guide alignment | Annual | 8 hours | Lift specialist |
9. Spare Parts References
| Component Description | Specify | UNITEC category |
|---|
| Wire rope | Steel 10mm 8x19 | Ropes_Suspension |
| Parachute jaws | Treated steel | Safety_Mechanics |
| Guide lubricant | Industrial viscosity ISO 68 | Consumables |
To purchase components, consult our online technical catalogue: https://www.unitecd.com/e-catalog/
10. Regulatory References
- UNI EN 81-20: Safety rules for the construction and installation of elevators.
- UNI EN 81-50: Design rules, calculations, exams and tests.
- Machinery Directive 2006/42/EC.
