1. Description of the problem and scope of application
This manual is intended for the systematic diagnosis and elimination of malfunctions associated with jamming and overloading of chain conveyors, which are critical for the uninterrupted operation of industrial production in Ukraine. Jamming and overloading can result in significant downtime, equipment damage, and increased operating costs. The guide covers common causes such as chain elongation, sprocket wear, lubrication system failure, and build-up of transported material. These problems can occur on a variety of chain conveyors used in the automotive, aerospace, food, chemical, and energy industries. All faults that cause a production line to stop are classified as critical.
2. Safety measures
WARNING! All standard safety procedures must be strictly followed before starting any diagnostic or repair work on the chain conveyor. Failure to follow these instructions could result in serious injury or death.
- LOCKOUT/MARKING (LOTO): Be sure to completely lockout and tag out all energy sources (electrical, hydraulic, pneumatic) in accordance with the internal rules of the enterprise and the requirements of DSTU EN 1037:2003 (Safety of machines. Prevention of unexpected start). Make sure that the conveyor is completely de-energized and cannot be accidentally started.
- RESIDUAL ENERGY: Be careful of stored energy in springs, tensioners, hydraulic cylinders, and lifted loads. Ensure that all potential sources of residual energy are released or contained before starting work.
- PERSONAL PROTECTIVE EQUIPMENT (PPE): Always use appropriate PPE: safety glasses, work gloves (according to EN 388), safety shoes with metal toe (according to EN ISO 20345), helmet. When working in dusty or noisy conditions, use a respirator (EN 149) and hearing protection (EN 352).
- INDUSTRY STANDARDS: Comply with the safety requirements set forth in DSTU ISO 12100:2016 (Machine safety. General design principles. Risk assessment and risk reduction).
- MOVING PARTS: Never insert hands or tools into moving parts of the conveyor. Even when the conveyor is stopped, there is a risk of material falling or shifting.
3. Necessary diagnostic tools
For accurate diagnosis of chain conveyor malfunctions, you will need the following set of tools:
| Name of the tool | Specification / Model | Measuring range | Purpose |
|---|---|---|---|
| Measuring tape / Ruler | Steel, accuracy class II (DSTU EN ISO 376:2018) | 0-5000 mm | Measurement of chain elongation, distances |
| Vernier caliper | Digital, 0-300 mm, accuracy 0.02 mm (DSTU ISO 13385-1:2018) | 0-300 mm | Accurate measurement of pin diameters, sprocket teeth thickness |
| Chain gauge / Chain wear template | Corresponding to the type and pitch of the chain (for example, for roller chains DSTU ISO 606:2015) | Step deviation ±0.5% | Quick check of chain extension |
| Thermal imager / Pyrometer | Range -20°C to +400°C, accuracy ±2°C | Temperature | Detection of overheating zones (bearings, chain, gearbox) |
| Vibration meter | Vibration analyzer, range 0.1-1000 mm/s, frequency 10 Hz - 10 kHz | Vibration speed (mm/s) | Diagnosis of wear of bearings, sprockets, imbalance |
| Tachometer | Optical/contact, 0-20000 rpm, accuracy ±0.05% | Rotation speed (rpm) | Conveyor speed compliance check |
| Torque wrench | Range 10-300 Nm, accuracy ±4% (DSTU ISO 6789-1:2018) | A turning point | Tightening fasteners of sprockets, bearings |
| Manometer | Range 0-60 bar, accuracy class 1.6 | pressure | Checking pressure in hydraulic tension systems |
| Multimeter | Digital, True RMS (DSTU IEC 61010-1:2014) | Voltage, current, resistance | Diagnostics of electrical components (engine, sensors) |
| Endoscope / Videoscope | Diameter 6-10 mm, length 1-5 m | Visual inspection | Inspection of hard-to-reach areas of the chain and sprockets |
4. Initial assessment checklist
Before starting a detailed diagnosis, it is necessary to collect as much information as possible about the operating conditions of the conveyor and the history of the malfunction. This will help narrow down the potential causes.
| Parameter | What to observe / Record | Importance |
|---|---|---|
| Description of the malfunction | Exact description of the symptom: the conveyor has stopped, it works jerkily, it makes an unusual noise, the overload protection has tripped. | Critical |
| Time and date of the malfunction | Record the exact time and date of the problem. | High |
| Production history | What product was transported, what was the load intensity before the failure? Did the parameters deviate from the norm? | High |
| Service history | When was the last scheduled maintenance (MO) performed? What works were performed? (Chain replacement, lubrication, tension adjustment) | High |
| History of breakdowns | Have there been similar malfunctions before? What was the reason and how was it eliminated? | High |
| External inspection | The presence of visible damage, deformations, foreign objects on the conveyor, traces of friction, lack of lubrication. | Critical |
| Noise and vibration | Assessment of the presence of unusual noises (creaking, knocking, howling) or increased vibration. | High |
| Temperature | Measure the temperature on the gearbox, bearings, chain (using a thermal imager/pyrometer). | average |
| Sensor readings | Check the readings of overload sensors, limit switches, and position sensors. | High |
| Electrical parameters | If possible, record the current and voltage on the electric motor before or during the malfunction. | average |
5. Systematic diagnosis: Sequence scheme
This chapter offers a step-by-step approach to diagnosis based on primary symptoms.
- Symptom: Conveyor has stopped, overload protection has tripped, or motor hums but conveyor does not move.
- Step 1.1: Visual inspection
- Check: Are there visible foreign objects jamming the chain or transported material?
- If yes:
- Probable cause: Jamming by foreign object or material accumulation.
- Actions: Go to section 6, 7.4 and 8.4.
- If not:
- Check: Is there excessive material accumulation along the conveyor path, on the sprockets or in the chutes?
- If yes:
- Probable cause: Overload due to material accumulation.
- Actions: Go to section 6, 7.4 and 8.4.
- If not:
- Check: Has the chain slipped off the sprockets or broken?
- If yes:
- Probable cause: Excessive chain elongation, critical sprocket wear, or slack tension.
- Actions: Go to section 6, 7.1, 7.2 and 8.1, 8.2.
- If not: Continue diagnostics.
- Step 1.2: Check for mechanical resistance (with power off)
- Actions: Try manually winding the circuit (assuming safe access and LOTO).
- If the chain moves with excessive resistance:
- Check: Are there areas of increased friction, jammed chain rollers, jammed tension station or drive bearings?
- If yes:
- Probable cause: Mechanical jamming, component wear, lubrication failure.
- Actions: Go to Section 6, 7.1, 7.2, 7.3, 7.4 and 8.1, 8.2, 8.3, 8.4.
- If not, but resistance is present:
- Probable cause: Gear or motor problems.
- Actions: Drive diagnostics are required. Beyond the scope of this guide.
- If the chain moves freely, but the conveyor does not start:
- Probable cause: Problems with the drive (motor, gearbox) or control system.
- Actions: An electrical part or actuator diagnosis is required. Beyond the scope of this guide.
- Step 1.1: Visual inspection
- Symptom: Conveyor works jerkily, unusual noises (creaking, knocking) or increased vibration are heard.
- Step 2.1: Visual inspection of the chain and sprockets (at LOTO)
- Check: Does the chain sag between the sprockets more than normal? (Check the tension according to the manufacturer's instructions, usually 1-2% sag from the wheelbase).
- If yes:
- Probable cause: Chain lengthening.
- Actions: Go to section 6, 7.1 and 8.1.
- If not:
- Check: Do the sprocket teeth have signs
- Step 2.1: Visual inspection of the chain and sprockets (at LOTO)
