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I. General Information

Chains normally consists of sidebars (Plate), pins, bushings rollers & Connecting pins.

The plate is the component that bears the tension placed on the chain. Usually this is a repeated loading, sometimes accompanied by shock. Therefore, the plate must not only a great tensile strength, but also must hold up to the dynamic forces of load and shock. Further more, the plate must meet environment resistance requirements.

The pin is subject to shearing and bending forces transmitted by the plate. At the same time, it forms a load-bearing part, together with the bushing, when the chain flexes during sprocket engagement. Therefore, the pin needs high tensile and shear strength, resistance to bending, and also must have sufficient endurance against shock and wear.

The bushing is subject to shearing and bending stresses transmitted by the plate and roller, and also gets shock loads when the chain engages the sprocket.

In addition, when the chain articulates, the inner surface forms a load-bearing part together with a pin. The outer surface also forms a load- bearing part with the roller’s inner surface when the roller rotates on the rail or engages the sprocket. Therefore, it must have great tensile strength against shearing and be resistant to dynamic shock and wear.

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The roller is subject to impact load as it strikes the sprocket teeth during the chain engagement with the sprocket. After engagement, the roller changes its point of contact and balance. It is held between the sprocket teeth and bushing, and moves on the tooth face while receiving a compression load.

Furthermore, the roller’s inner surface constitutes a bearing part together with the bushing’s outer surface when the roller rotates on the rail. Therefore, it must be resistant to wear and still have strength against shock, fatigue, and compression.

These are the parts that prevent the outer plate from falling off the pin at the point of connection.

Side bars of all chain are heat-treated for strength and wear resistance. Bushings and pins are assembled to side bars with controlled interference fits. These relatively heavy interference fits provide a significant improvement in side bar fatigue strength. As the pin interference fit increases, the side bar fatigue strength increases. The optimized interference utilized in TIDC chain was established by comprehensive fatigue testing.

Do not heat chain side bars or grind pins for ease in assembly. Side bars fatigue may result and chain warranty will be void.

Fatigue resistance is critical in heavy duty bucket elevator applications. These applications normally see high loads and experience many load cycles in a very short time. Chains with low fatigue strength will not stand up to this rigorous duty and will break prior to normal chain replacement from wear.

TIDC Bucket Elevator Chains are specially designed to withstand the severe demands placed on bucket elevators.

TIDC Bucket Elevator Chain is specially designed for centrifugal discharge type bucket elevators. The ideal choice, this chain has induction-hardened pins, case-hardened bushings, and shot-peened link plates for superior fatigue strength and wear resistance.

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Unless otherwise specified, new conveyor chains are usually supplied in 3m (10ft.) lengths to facilitate handling. The chain is made in even numbers of pitches, with an inner link at one end and an outer link at the other end, so they may be easily joined together.

To connect the chain:

1. First fit the pinholes of the outer link plate to the bushing holes to be connected and insert the pins.

 Inserting the Pins

2. Hold the counter plate with a hammer and tap the pin heads with another hammer until the pins are completely inserted into the link plate.

Putting on the Link Plate

3. Insert new T-pins or cotter pins into the bearing pins and bend the ends to prevent loosening.

Inserting T-Pins or Cotter Pins

Note

Do Not Grind the Circumference of the Connector of the Side Bar Hole to Ease Insertion of the Connector.

Do Not Heat Side Bars to Ease Pin Insertion. Side Bar Fatigue may Result Which will Cause the Entire Chain and Bucket Assembly to Fall into the Boot of the Elevator.

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Before starting to install elevator chain, the foot shaft take up should be positioned at its upper end of travel to provide for maximum adjustment. To accomplish this, tie off the take up beam assembled in the top of the boot section.

For convenience in shipping and handling, chains are coiled in segments approximately 3 meters long. The chain can become twisted if improperly handled.

Newer pick up the chain by hooking into the center of a coil.

Avoid This

Support the entire coil.

Do This

Do not feed the chain into elevator on its side.

Avoid This

Do This

Assemble and disassemble chain quickly and safely in the elevator with the  portable tool.

After the chain connection has been made, check to determine if the joint is too tight, a sharp rap to the cotter end of the pin with a hammer will aid in relieving the tightness. This can be easily accompanied before buckets are attached.

The chain may now be installed in the elevator casing. The chain lengths should be connected together outside the elevator casing and fed in through the boot.

No more than 6 meters of chain should be connected together outside of the elevator during installation, to avoid twisting or bending. Be sure that the chain is oriented properly.

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Drop a line into the far-side of casing from the top. Using an air tugger or other means available, feed chain around the bottom of the foot wheel and upward to the top of the head wheel. At this time, tie off the chain, making sure chain is secure. Repeat the same procedure, feeding the chain upward on the opposite side of the casing. Connect chain at the head wheel maintaining firm grip on the chain while making connection. Return to the clean out door and connect the chain. Make last chain connection in boot after chain is installed.

Secure the chain in such a way, using a hoist for tying off to a structural member laid across the bearing angle, so that there is no chance of the chain running away and dropping into the boot. Do not mount buckets to chain until the chain has been installed in the elevator.

It is recommended that all elevators be equipped with a positive stopping device. This feature will eliminate extensive damage to the equipment by preventing a backward action of the elevator.

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1. Guards, access doors and covers must be securely fastened before operating this equipment.

2. Electrical interlocks to warn personnel and shut off power whenever discharge of elevator is interrupted.

3. Over load protection, Zero speed protection, Emergency stop switch and all other interlock keep in working condition.

4. Be sure all debris, foreign objects and tools are removed from the elevator inside and adjacent areas.

5. Confirm motor rotation. Ensure it is running in the right direction.

6. Auxiliary equipment feeding the elevator must be electrically interlocked with the elevator to prevent boot flooding when elevator is not in operation.

7. Complete one or two revolution of the chain and buckets by auxiliary drive or manual to check for proper assembly and clearances. If no difficulties are experienced during auxiliary drive rotation, run the elevator with out load for one hours .

Before start up, make sure there is no obstruction to free discharge of material.

Elevator should be started with empty buckets only. Starting under load places undue strain on chain. Therefore, it is imperative to allow all buckets to empty before stopping elevator.

Stop elevator only after feed has been stopped and elevator allowed to discharge the material.

Successful operation of any elevator is dependent on con feed. Material must be feed at a controlled rate within rated capacity or boot will flood and stall elevator.

Avoid loading buckets to the extent of material spilling back down into the boot section. Boot must not be allowed to pile up with spilled material.

The operator(s) should become familiar with all aspects of the construction and normal operating conditions of the equipments. Thereby, immediately recognizing an abnormal situation or operating condition before serious damage occurs

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Special tools or equipment recommended to maintain or service your elevator chain include a standard torque wrench, portable jack and hammers to be used when checking.

Material should be centrally delivered at the specified uniform rate. Avoid loading buckets to the extend that the material spills back down into the boot section. The boot itself must not be allowed to fill up with spilled material. Chain should be operated at its rated speed.

Chain life is generally considered to have expired when the chain does not engage properly with the sprocket / Traction wheel due to damage of its parts or elongation. The chain is usually replaced when this occurs. A long working life without unexpected trouble can be achieved if the chain is properly selected for the conditions of its application. To help prevent premature wear or damage, the following points should be checked.

1. Abnormal Noise

2. Vibration of the chain

3. Chain rising on the sprocket / Traction wheel

4. Chain winding around the sprocket / Traction wheel

5. Stiff bending of chain, or links

6. Amount and condition of lubrication

7. Whether the chain contacts the case

8. Appearance of the chain. Check for dirt, corrosion, damage on the outside surface of the roller, contact marks, etc. Also check the inside and edge surfaces of the link plate and edge surface of the pin.

9. Damage on the sprocket teeth / Traction wheel surfaces and side surfaces of teeth and engaging area

10. Abrasive stretch of the chain

11. Bending of chain and rotation of roller

If repeated loads in excess of the allowable load are applied to the chain, there is a strong possibility of fatigue breakage of the link plate. Fatigue breakage is difficult to anticipate until a crack is produced. Usually a crack develops at the edge of a hole or at the side of the link plate, as shown in the illustrations below. The presence of cracks should be checked carefully. Continuous checking can prevent accidents.

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Positions where cracks are likely to develop

Example of an expanding crack

Care should be taken to avoid repeated impact loads over the allowable load as fatigue breakage may occur. The roller should be checked in the same way as the link plate. If foreign objects interfere with the engagement of the roller and sprocket, the roller may be damaged and a crack may develop. Careful attention should be paid to this. Chains damaged due to fatigue breakage must be completely replaced.

Crack produced on the roller

Chain and sprocket engagement can be checked by observing the roller and tooth surfaces. The proper margin (A) and improper margin (B) are shown in the fig. The installation should also be checked. The normal area where wear will occur is slightly above the bottom of the lowest point between the sprocket teeth. If tension remains on the slack side, the roller will slightly touch the lowest point between the sprocket teeth. When an idler or tightener is used, wear will occur almost directly between the sprocket teeth.

Areas to Check for Sprocket Wear

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Once the elevator is placed in operation, Preventive maintenance program should begin.

1. The buckets should be checked periodically for loose bolts and build up of material. All damaged buckets should either be repaired or replaced to eliminate material falling into the boot.

2. Check the rubber lip or tongue plate on the discharge spout of the elevator, which should not touch with the bucket.

3. Check take up of bucket clearance with bottom of boot.

4. Side bars inner surfaces should be checked for wear. This is an indication of misalignment.

5. Loose or unseated pins are danger signals and could lead to a sudden and unexpected chain shut down.

6. Excess material building in the chain and attachments could cause improper seating on traction wheel rims / sprockets and rough elevator operation.

7. Round parts in chain; that is, the pins and bushings should be inspected for wear.

8. Traction wheel / Sprockets should be inspected for alignment and excessive wear.

1. Check motor load.

2. Check bucket fixing bolt missing & looseness.

3. Check boot for material build up and clean.

4. Check material build up in chain components and hammer it so that it can dislodge.

5. Check chain for connecting pin seating.

In addition to weekly inspection points, following pointes are to be checked

1. Check inside block links for wear

2. Check all side bars on bushing OD for wear.

3. Visually inspect clearance between each set of inner and outer side bars. Excessive clearance suggests pin fracture.

4. Check for loose segmental fasteners. Check torque values for segmental rim bolts.

5. Check segmental traction wheel unusual wear.

6. Check for loose or missing buckets.

7. Inspect and adjust tongue plate at discharge point for wear and replace if excessively worn.

8. Check gravity take up guides and stop blocks; check for free operation of take up guides, check for evidence of wear on guides.

In addition to weekly & Quarterly inspection points, following pointes are to be checked.

a) Traction wheel / Sprocket

1. Check for loose or missing segmental fasteners and torque values. If fasteners are missing, replace with proper diameter high strength type.

2. Check for evidence of axial movement of sprocket along shaft.

3. Check for evidence of unusual or excessive wear and replace sets of segments as required.

b) Gravity Take up

1. Check stop blocks; check for free operation of take up in guides; check for evidence of wear on guides.

c) Buckets

1. Check for loose or missing bucket fasteners.

2. Check for unusual wear patterns or damage buckets.

d) Drive station

1. Check head shaft bearings for evidence of wear.

2. Check foot shaft bearings and sleeves for evidence of wear.

e) Chain section

1. Check all side bars and bushing OD s for uneven or deep wear patterns.

2. Check inside blocks for unequal wear from traction wheel / Sprocket.

3. Check chain for missing T- pin.

4. Check for chain elongation wear.

5. Remove 5 or 10 pins at random and measure the pin OD and bushing ID. Hammer test all pins for soundness.

The correct amount of chain slack is essential for proper operation of the chain. When the chain is too tight, working parts such as chain, sprocket wheel, shaft, bearing, etc. carry a much heavier load. On the other hand, too much slack is also harmful and causes the chain to climb the sprocket teeth.

The chain has a tendency to stretch a certain amount at the beginning of operation due to slight distortion of its component parts. After such initial elongation, the chain stretches slightly, but constantly, by normal wear. To maintain proper chain tension, adjustments, if necessary, should be made at regular intervals. Neglect of careful inspection increases the chance of an accident.

Frequency of adjustment:

1st week - once a day

2nd ~ 4th week - twice a week

Thereafter - twice a month

Note:

The above frequency schedule is based on 8 hours operation a day. When working hours are increased, the frequency of adjustment should be increased accordingly.

This can be easily accomplished when take-ups are cooperating screw type or counterweight type. Where two parallel chains are adjusted by two independently operated take-ups, care must be taken to ensure even stroke on both the left and right side. An uneven adjustment will cause the link plate and the side of the sprocket teeth to interfere with each other and result in an overload condition.

When the chain engages with the sprocket or runs on a curved rail section, the chain flexes causing the chain to stretch. In most cases, this is due to wear of the bearing parts such as the pins and bushings. As chain pitch elongation increases, the chain tends to climb the top of sprocket. This makes smooth operation of the conveyor impossible. The limit of pitch elongation is generally 2% - 6 % of the chain pitch.

Places to Measure Chain Elongation

Fig. indicates the way to measure chain pitch. Using a steel tape measure, measure as many pitches as possible (at least 4 pitches required). Measuring points should be properly determined according to (A), (B) or (C) in Fig., depending on the wear condition of the conveyor chain. The chain pitch elongation per link is to be computed by comparing the actual pitch measured against the original chain pitch.

Chain Pitch elongation can then be calculated.

Standard Length = Chain Pitch x Number of Links

Note

When measuring, use at least 6 to 10 links to help keep any measuring error to a minimum. When measurement cannot be done with a vernier, it is possible, though less accurate, to use a tape measure. If a tape measure is used, the measured length should be as long as possible.

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After a certain period of time, wear will eventually appear on the chain and sprocket. The life of conveyor chain depends on the wear of each component part and on pitch elongation. Careful inspection is required more often than for power transmission roller chain.

The life of the conveyor chain component parts is shown below. TIDC recommends that periodic inspections of the wearing parts are conducted and that care be taken to ensure that proper maintenance is carried out. Also, a schedule for changing the chains should be established.

When wear between the rail, bushing and roller causes the under surface of the link plate to contact the rail, the chain has usually reached the end of its usability. As shown in Fig, when the link plate starts contacting the rail, rolling contact suddenly turns into sliding contact between the link plate and rail, resulting in greater wear, an increase in chain tension and a reduction in transmitted horsepower. Such wear generally appears on horizontal or inclined apron conveyors, slat conveyors, etc.

Roller Wear

Where a curved section of rail is provided, the allowed wear amount is decreased by a dimension equivalent to "S". More care must be taken to observe wear than with horizontal sections.

The chain life has expired as soon as holes or crevices appear on the rollers due to wear.

Bushings are generally useable until holes appear. Holes may appear as a result of conveying very abrasive materials such as iron ore powder, coke, etc.

Reciprocal friction between inner and outer link plates and contact between side surfaces of rollers and inside surfaces of link plates causes wear as indicated by (A) and (B) in Fig.

If the amount of wear exceeds 1/3 of the original plate thickness, the tensile strength of the chain will be reduced. When link plate wear appears faster than wear of other component parts, misalignment of the conveyor during installation is the cause in most cases. Misalignment can also develop during operation of the conveyor. Therefore, careful inspection is required to ensure maximum working life.

Please check the following items:

a. Correct alignment of driving and driven sprockets

b. Correct alignment of shafts in horizontal and vertical planes

c. Preciseness of level gauge and accurate leveling

When the sprocket is worn, the chain tends to cling to the sprockets and vibrate. The amount of allowable wear depends on the conveyor type and chain size, but generally, wear to a depth of 3mm (0.12") to 6mm (0.24") is a sign that the existing sprocket should be repaired or replaced with a new one to ensure continued chain life. One of the following means may be used to extend sprocket life:

a. Cut section (A) shown in Fig. with a grinder

b. Reverse the sprocket to change the engaging area of the tooth

c. Surfacing can be made using a welding rod to obtain the correct tooth profile. However, it is more effective to replace the existing sprocket with a new one.

If the sprocket teeth are worn as shown in Fig. , the alignment of the sprockets may be incorrect. Proper axial alignment of the sprockets will help reduce or even eliminate this type of wear.

Sprocket wears

Fig. Sprocket Tooth Wear

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1. Mechanical wear

When conveyor chain is used under reasonable conditions and a normal atmosphere, mechanical wear causes the bearing surface of the chain to shine brightly. With proper lubrication, further life can be assured.

Mechanical Wear

2. Wear caused by conveyed material

Material having excessive wear characteristics tends to stick to the chain and to wear the surface of the chain due to reciprocal friction between the material and chain. Under such conditions, care should be taken to prevent material from falling on the chain. For extra protection, chains should have higher wear resistant specifications.

3. Wear due to corrosion

Conveyor chain used in applications where acidic or alkaline chemicals are present, will be subject to corrosive wear as well as mechanical wear. To protect against the chemical corrosion accompanying mechanical wear, stainless steel is recommended.

Wear from corrosion

4. Electrochemical corrosion

When the chain is splashed with water, and then enters chemical solutions, the surface of the sliding area (i.e., Pin/Bush, Bush/Roller) is exposed to electrochemical corrosion, one of the most damaging types of corrosion.

Electrochemical corrosion

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This Manual Contains Instructions for maintenance of TIDC chains. The reliable operation and long service life of these chains depends to a greater extend on the care taken during installation and operation and the degree of maintenance.

Safety is a factor that must be considered at all times in the operations and mechanical equipment. Use of proper tools and methods can prevent serious accidents that may result in injury to the operators and fellow workers.

Failure to Observe and Follow all Safety Instructions may Result in Serious Personal Injury or Property Damage.

Use care to prevent injury, Comply with the following to avoid serious personal injury

1. Guards must be provided on all chain and sprocket installations in accordance with provisions of ANSI/ASME B15.1 - 1992 "Safety Standards for Mechanical Power Transmission Apparatus," and ANSI/ASME B20.1 - 1993 "Safety Standards for Conveyors and Related Equipment," or other applicable safety standards. When revisions of these standards are published, the updated edition shall apply.
2. Always lock out power switch before installing, removing, lubricating or servicing a chain system.
3. When connecting or disconnecting a chain:

a) Eye protection is required. Wear safety glasses, protective clothing, gloves and safety shoes.

b) Support the chain to prevent uncontrolled movement of chain and parts.

c) Use of pressing equipment is recommended. Tools must be in good condition and properly used.

d) Determine correct direction for pin/rivet removal or insertion.

e) Steady force, such as mechanical or hydraulic press, is preferred. If impacting force such as hammer is used, take special precautions to avoid metal chips from the chain or tools.