1. Scope and Objective
This technical guide covers procedures for inspecting, measuring alignment, checking joint plates and end stops for industrial raceways and rails. It applies to handling systems, overhead cranes, gantry cranes and transfer carts commonly used in the aerospace and energy sectors. The goal is to ensure operational safety, prevent premature component failure, optimize equipment life, and maintain operating precision of transportation systems.
This maintenance is essential to identify any degradation likely to compromise the structural stability and dynamic performance of the equipment, as well as to comply with industrial standards such as EN 15011 (Overhead cranes and gantry cranes) and the NF directives relating to lifting and handling equipment.
2. Safety Precautions
WARNING: Before any intervention, it is obligatory to isolate the equipment and lock it out (lockout/tagout) to prevent any accidental start-up. Check the absence of electrical voltage and residual energy. Always use appropriate personal protective equipment (PPE) and follow working at height procedures if necessary. Ensure that the work area is marked off and secured against unauthorized access. Failure to follow these instructions could result in serious injury or death.
WARNING: Risk of crushing or pinching. Never place hands or other body parts under or between potentially moving or loaded components. Use suitable supports or wedges to stabilize the elements before handling. Check the integrity of access structures and scaffolding.
Recommended PPE includes: safety helmet, protective glasses, cut and impact resistant work gloves, safety shoes with anti-puncture toe cap and sole, high visibility clothing and safety harness with lifeline if working at height.
3. Tools and Materials Required
Preparing the appropriate tools is a critical step in performing this procedure efficiently and safely.
| Tool / Material Name | Specification / Features | Quantity |
|---|---|---|
| Laser alignment system | Accuracy of ±0.1 mm/10m, with parallelism and level measurement function | 1 |
| Precision level (digital or bubble) | Accuracy of 0.02 mm/m (20 µm/m) | 1 |
| Feeler gauge (shim set) | Range 0.05mm to 1.00mm, 0.05mm increments | 1 game |
| Steel measuring tape, certified | Minimum length 10 m, precision class II | 1 |
| Torque wrench | Range 50 Nm to 300 Nm (for M16-M20 bolts) | 1 |
| Torque wrench | Range 200 Nm to 800 Nm (for M24-M30 bolts) | 1 |
| Socket wrench and spanner set | Metric sizes (19mm to 46mm) | 1 game |
| Wire brush | For cleaning rail surfaces and bolts | 2 |
| Cleaning cloths | Lint-free | 1 packet |
| Industrial degreaser | Complies with environmental standards, without residue | 1 aerosol |
| Permanent marker | High visibility | 2 |
| Digital camera / Smartphone | With time stamp function for documentation | 1 |
| Personal Protective Equipment (PPE) | Helmet, glasses, gloves, safety shoes, fluorescent vest | According to staff |
4. Pre-Maintenance Inspection Checklist
Before beginning detailed maintenance procedures, a preliminary visual inspection is recommended to identify obvious problems.
| Element | Verification | Acceptance/Rejection Criteria | Notes |
|---|---|---|---|
| Work area | Absence of obstacles, cleanliness | Clear, clean, sufficient lighting | Any obstacle must be removed |
| Rails (surface) | Presence of foreign bodies, debris, rust | Clean running surface, free of excessive rust, chips or dirt | Clean if necessary before measurement |
| Rails (general) | Visible damage: cracks, deformation, abnormal wear | No visible cracks, no plastic deformation greater than 0.5 mm over 100 mm | Note any anomalies for further inspection |
| Splint plates | Cracks, deformations, signs of movement | Intact, stable position, without deformation | Signs of movement (shininess, rust) around the bolts |
| Bolts | Loose, missing, damaged bolts | All bolts present, visually tightened, heads intact | Check for tightening marks |
| End stops | Structural integrity, fixation | Solid fixation, no visible deformation, absorption device intact | Check the condition of the cushioning buffers |
| Rail supports | Cracks, deformations in support structures | Intact, without visible deformation | Note any damage to the concrete or steel support |
5. Walkthrough
5.1. Work Area Preparation and Documentation
Demarcate the inspection and maintenance area using tape or barriers. Post safety signs.
Ensure all equipment movements on the rails are interrupted and logged (LOTO). Check for the absence of electrical, hydraulic or pneumatic power.
Position the equipment to be inspected in a safe and accessible area, if required by the maintenance plan.
Gather all the tools and materials listed in section 3. Check that they are in good working order and their calibration.
5.2. Rail Alignment Measurement
Cleaning Surfaces: Thoroughly clean the running surface of the rails with a wire brush and degreaser to remove any dirt or rust that could distort the measurements.
Laser System Installation: Position and calibrate the laser alignment system according to the manufacturer's instructions. Unstable installation or incorrect calibration will distort all measurements.
Horizontal Alignment Measurement (Laterality): Place the laser targets at regular intervals (e.g. every 5 meters) along the rail. Record horizontal deviations from an established reference axis. The typical tolerance for overhead crane systems is ±1 mm over a 10 meter section. For high precision transfer systems, this tolerance can be reduced to ±0.5 mm over the same length.
- Common error: Ignoring ambient temperature variations which can affect laser scanning over long distances. Carry out measurements under stable conditions.
Vertical Alignment (Level) Measurement: Use the precision level or level function of the laser system. Measure vertical deviations at similar intervals. The vertical tolerance should generally not exceed ±0.5 mm per meter of rail length, nor a maximum of ±5 mm over the entire length of the raceway.
- Common error: Failing to compensate for irregularities in the rail support surface, which may mask a real alignment problem.
Gauge Measurement: Use the tape measure or a specific track gauge. Measure the spacing between the two rails at regular intervals (eg: every 3 meters). Gap must meet OEM specifications, with a tolerance of ±1mm.
- Common error: Using an uncertified or fabric measuring tape, resulting in inaccurate measurements due to stretching or deformation.
Documentation of Measurements: Record all measurements and deviations in the inspection report. Take photos of critical areas or anomalies.
5.3. Checking Splint Plates and Fixings
Visual Inspection of Joint Plates: Examine each joint plate for cracks, deformation, wear marks or signs of relative movement between the plate and the rail (e.g. scuff marks, localized polishing, friction rust). The plates must be in solid contact with both rail sections.
Bolt Inspection: Check the condition of each bolt, nut and washer. Look for corrosion, damaged threads, bent bolt heads, or loose nuts. Make sure the bolts are of the correct strength class (eg: 8.8, 10.9) according to the manufacturer's specifications.
- Common error: Neglecting inspection of washers, whose deformation may indicate insufficient or excessive tightening, or wear.
Checking Tightening Torque: Use the calibrated torque wrench to check the tightening torque of all joint plate bolts. Apply the torque specified by the manufacturer (indicative examples: M20 Grade 10.9: 300 Nm to 350 Nm; M24 Grade 10.9: 500 Nm to 600 Nm). Proceed with a slight loosening motion then re-tightening to the required torque for each bolt, starting with the center bolts and working outward in a crisscross fashion.
- Common error: Tightening without a method or torque wrench, which can result in under-tightening (loosening) or over-tightening (bolt breakage or plate damage).
- Visualizing the check: Mark each bolt checked with a permanent marker to indicate that it has been checked for the correct torque.
Cleaning and Protection: After checking, clean the areas and apply anti-corrosion protection if specified by the maintenance plan.
5.4. Checking End Stops
Visual Inspection: Examine the physical integrity of each end stop. Look for signs of warping, cracking, excessive corrosion or impact damage. The body of the stop and its attachment system to the rail or to the structure of the raceway must be in perfect condition.
Checking the Fixation: Make sure that the stopper is securely attached to its support. Check the tightening torque of the fixing bolts according to the manufacturer's specifications (e.g. M16 Grade 8.8 bolts at 150 Nm, M20 Grade 8.8 bolts at 250 Nm). Any loose fasteners must be tightened to the prescribed torque.
Inspection of the Energy Absorption Device: If the stopper is equipped with an elastomer buffer (rubber, polyurethane) or a hydraulic shock absorber, inspect its condition.
- For elastomeric pads: check for tears, permanent deformation, excessive hardening or softening.
- For hydraulic shock absorbers: look for fluid leaks, bent or damaged rods. Check the oil level if available and specified by the manufacturer.
- Common error: Ignoring the degradation of the absorbent pads, which reduces the effectiveness of the stop and can cause violent impacts to the structure.
Safety Distance Measurement: Verify that the distance between the moving equipment (e.g. bridge trolley) and the end stop complies with safety specifications, allowing a controlled stop even in the event of failure of the limit devices.
6. Post-Maintenance Verification Checklist
After making adjustments and checks, it is essential to ensure the quality of the work accomplished.
| Test | Expected Result | Actual Result | Compliant / Non-Compliant |
|---|---|---|---|
| Horizontal alignment | Deviations < ±1 mm/10m or as specified | ||
| Vertical alignment | Deviations < ±0.5 mm/m or as specified | ||
| Rail gauge | Meets OEM specifications ±1mm | ||
| Tightening torque of the sides | All bolts at the prescribed torque (e.g.: M24 at 550 Nm ±10%) | ||
| Integrity of the joint plates | No cracks, warping or signs of movement | ||
| End stops | Strong fixation, absorption device intact, no deformation | ||
| Cleanliness of the area | Clean and unobstructed work area | ||
| Documentation | Complete and signed maintenance report |
7. Troubleshooting Guide
This table provides assistance for common problems encountered with raceways and rails.
| Symptom | Probable Cause | Corrective Action |
|---|---|---|
| Excessive vibration of rolling equipment | Horizontal or vertical misalignment of the rails | Measure alignment and correct deviations. Check straightness and parallelism. |
| Abnormal wear of wheels or rail sides | Incorrect rail gauge (too narrow or too wide); misalignment. | Check rail gauge and alignment. Adjust to OEM tolerances. |
| Clicking noise when the sides pass | Loose joint bolts; excessive play at joints; deformation of the plates. | Check and tighten the bolts to torque. Inspect the plates for deformation and replace if necessary. |
| Sudden and violent stopping of the equipment at the end of the stroke | End stop damaged; faulty energy absorption device; stopper poorly fixed. | Inspect the stop and its buffer. Replace damaged components. Check the fixation. |
| Difficulty of equipment moving along the rail | Obstruction on the rail; excessive friction due to misalignment; surface contamination. | Clean the rail. Check alignment. Inspect the wheel bearings. |
| Cracks or corrosion on the joint plates | Occasional overload; fatigue constraints; corrosive environment; incorrect tightening. | Replace damaged plates. Review the tightening procedure. Apply adequate protection. |
8. Recommended Maintenance Schedule
A regular maintenance program is essential for reliability and safety.
| Task | Frequency | Estimated Duration | Skill Level |
|---|---|---|---|
| General visual inspection of rails and supports | Monthly | 1 hour / 100m | Junior Maintenance Technician |
| Visual inspection of joint plates and bolts | Quarterly | 0.5 hour / 100 m | Junior Maintenance Technician |
| Rail alignment measurement (laser) | Annual | 4 hours / 100m | Confirmed Maintenance Technician |
| Checking the tightening torque of the plates and supports | Bi-annual | 2 hours / 100m | Confirmed Maintenance Technician |
| Detailed inspection and verification of end stops | Annual | 1 hour / stop | Confirmed Maintenance Technician |
| Thorough cleaning of the raceways | Depending on the environment (min. Semi-annual) | Varies | Junior Maintenance Technician |
9. Spare Parts Reference
Maintaining a stock of critical spare parts is crucial to minimizing downtime. UNITEC-D GmbH offers a comprehensive range of components.
| Part Description | Typical Specification | UNITEC category |
|---|---|---|
| High strength joint bolt | M24 x 100mm, Grade 10.9, DIN 931 | Industrial Bolts |
| Self-locking nut | M24, Grade 10, DIN 982 | Nuts and Washers |
| Wide flat washer | M24, Hardened steel, DIN 7989 | Nuts and Washers |
| Rail joint plate | Type A75 or A100, S355JR steel, machined | Fixing Components |
| Stop cushioning pad | Polyurethane, Hardness 90 Shore A, 200x150x100mm | Industrial Shock Absorbers |
| Running rail | A75 profile, length 6 m, UIC 860-0 steel | Track Profiles |
| Thread repair kit | For M16 to M30 | Specific Tools |
For any spare parts, consult our online catalog: https://www.unitecd.com/e-catalog/
10. References
- EN 15011: Overhead cranes and gantry cranes.
- EN 13001-2: Crane safety – General design – Part 2: Load effects and stress verification.
- NF E 52-210: Lifting devices with suspended load. General rules for design.
- ISO 898-1: Mechanical characteristics of carbon steel and alloy steel fasteners — Part 1: Bolts, screws and studs with specified quality classes — Coarse pitch thread and fine pitch thread.
- OEM technical documentation specific to the affected equipment.
