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Slack Rope & Automatic Rope Slip Protection for Winder – DGMS Requirements, CMR/MMR Provisions, Working & 25 MCQs

Slack Rope & Automatic Rope Slip Protection for Winders – DGMS Requirements (CMR + MMR) + 25 MCQs

🧾 DETAILED NOTES

1️⃣ Introduction

Winders are critical mining systems used for man-winding, material winding, coal/ore hoisting, shaft sinking, and incline transport. Because the hoisting rope is the main life-line of a mine, DGMS mandates multiple safety devices. Two of the most important are Slack Rope Protection and Automatic Rope Slip Protection. These prevent fatal accidents such as cage overwind, rope detachment, drum slipping, uncontrolled movement, and rope entanglement.

2️⃣ What is Slack Rope?

Slack rope occurs when the winding rope loses tension and becomes loose. This is deadly because the rope may jump the drum, derail from pulleys, or the cage may tilt or free fall.

3️⃣ What is Rope Slip?

Rope slip occurs when the rope slips over a friction pulley (Koepe) or the grip between the rope and drum reduces. This out-of-sync movement can lead to overwind, overwriting of the cage, or free fall.

4️⃣ DGMS Objective of These Provisions

  • To ensure cage safety and prevention of overwind.
  • To ensure no free fall occurs.
  • To ensure the rope always remains under tension.
  • To provide automatic stopping in case of failure.

5️⃣ Legal Framework

Regulation / Act Description
CMR 2017 – Reg. 98-101 Winding Equipment, Safety Devices, Precautions & Automatic Contrivances.
MMR 1961 – Reg. 65-67 Winding Engines, Safety Devices & Shaft fittings.
DGMS Tech Circular 01/2008 Winder safety devices.
DGMS Tech Circular 03/2015 Koepe winder safety.
DGMS Tech Circular 02/2019 Rope slip detection.

6️⃣ Slack Rope Protection System

A slack rope device must automatically detect rope loosening, stop the winder immediately, and apply the brakes. It must only be resettable manually by an authorized person. Detection methods include tension sensors (load cells), hydraulic devices, or electrical limit switches.

7️⃣ Automatic Rope Slip Protection

Mandatory for all winders, especially Koepe (friction) winders, this system detects differential speed by comparing the drum speed (via an encoder) with the actual rope movement. If a slip is detected, it triggers an emergency brake. This is crucial as rope slip can be caused by oil/grease on the drum, worn grooves, or improper friction.

8️⃣ Key Safety Requirements (DGMS)

  • Mandatory: Slack rope protector, Rope slip detector, and Automatic brake application.
  • Must require a manual reset by a competent person.
  • Must be interlocked with the brake system.
  • Weekly testing and monthly calibration are required.

⚡ QUICK ONE-LINERS

  • Slack rope = loss of rope tension.
  • Rope slip = rope movement without drum movement.
  • Mandatory under CMR Reg. 99 & MMR Reg. 66.
  • Koepe winders are highly susceptible to rope slip.
  • Slack rope device stops winder instantly.
  • Rope slip protection compares drum speed vs. rope speed.
  • Weekly test = compulsory.
  • Manual reset required after tripping.
  • Rope slip may cause overwind or cage crash.
  • DGMS Tech Circular 03/2015 is specific to Koepe winders.

🧠 DESCRIPTIVE MODEL Q&A

Q. Explain the need for slack rope and rope slip protection devices in winders as per CMR and MMR.

Answer:
Slack rope and rope slip are critical hazards in winding systems. Slack rope (loss of tension) can cause the rope to derail from the pulley or drum, leading to cage instability or entanglement. Rope slip (common in Koepe winders) is when the rope moves independently of the drum, leading to loss of cage position, overwinding, or free fall.

DGMS mandates automatic slack rope and rope slip protection under CMR 2017 (Reg. 99) and MMR 1961 (Reg. 66). These devices detect tension loss or differential speed and automatically apply the emergency brakes. Weekly testing, monthly calibration, and manual reset features are required to ensure reliability and prevent catastrophic accidents.

🧮 25 MCQs (5 Options Each — Randomized Answers)

Q1. Slack rope refers to:

Solution: Slack rope is the condition where the rope becomes loose due to a lack of proper tension (e.g., cage gets stuck).

Q2. Regulation dealing with slack rope protection in coal mines:

Solution: Regulation 99 of CMR 2017 lists the mandatory safety devices for winders, including slack rope protection.

Q3. Rope slip is common in:

Solution: Koepe (friction) winders rely entirely on friction between the rope and the drive pulley, making them susceptible to slip.

Q4. Device comparing drum vs rope speed:

Solution: A rope slip detector compares the drum's rotational speed (from an encoder) with the rope's actual speed.

Q5. Slack rope may cause:

Solution: If the rope becomes slack, the cage can get stuck, tilt, or even free-fall a short distance, causing catastrophic damage.

Q6. Which DGMS circular relates to Koepe winder safety?

Solution: DGMS Tech Circular 03/2015 provides specific guidelines for the safety of Koepe (friction) winders.

Q7. Mandatory testing frequency for these devices:

Solution: These critical safety contrivances must be tested at least once every seven days.

Q8. Rope slip occurs due to:

Solution: Rope slip is a failure of the friction grip between the rope and the winder drum/pulley.

Q9. Rope slip protection is essential for:

Solution: It is a critical safety device, especially when persons (man-winding) are being transported.

Q10. Slack rope detector must:

Solution: The device must be interlocked to automatically cut power and apply the brakes when slack rope is detected.

Q11. Which is NOT a cause of slack rope?

Solution: Proper tension is the *correct* operating state; all other options are causes or descriptions of a slack rope condition.

Q12. Rope slip protection compares:

Solution: Its function is to detect a mismatch (differential) between the winder drum's rotation and the rope's actual speed.

Q13. Slack rope device is interlinked with:

Solution: It must be interlocked with the winder's main control and brake system to trigger an emergency stop.

Q14. Winder operator must test devices:

Solution: A check of all safety devices is mandatory before any shift where persons are to be transported.

Q15. Rope slip may result in:

Solution: If the rope slips, the depth indicator becomes inaccurate, which can lead to an overwind (cage going too high or too low).

Q16. MMR regulation for winder safety:

Solution: Regulations 65 (Winding Engines) and 66 (Safety Devices) of MMR 1961 cover these requirements.

Q17. Slack rope detection uses:

Solution: Modern systems use load cells or tension sensors to continuously measure rope tension and detect slack.

Q18. Rope slip detectors in friction winders ensure:

Solution: The detector's purpose is to monitor the friction grip; if it fails (slips), the detector trips the winder.

Q19. Automatic brake must be:

Solution: All safety brakes must be "fail-safe," meaning they apply automatically in the event of power loss or a trip signal.

Q20. Rope slip risk increases due to:

Solution: Any lubricant like oil or grease on the drum or pulley groove drastically reduces friction and causes rope slip.

Q21. Slack rope protection is required for:

Solution: This is a mandatory safety device for all winding systems (Drum, Koepe, etc.).

Q22. Calibration of detector done:

Solution: Monthly calibration is a standard requirement to ensure the electronic sensors and trips are accurate.

Q23. Differential speed detection uses:

Solution: Encoders are digital devices that measure the rotation (speed) of the drum, which is then compared to the rope speed.

Q24. Rope slip detection prevents:

Solution: By detecting a slip and applying the brakes, the system prevents an uncontrolled descent or free fall of the cage.

Q25. Final objective of winder protections:

Solution: All safety devices, including these, are installed to achieve the ultimate goal of "Zero Harm" in mining operations.

🔗 INTERNAL LINKS

Related Topic Read More On...
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CMR 2017 CMR 2017 Part 2 - Working & Supervision Rules
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