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4A Torque Wrenches-1 “Quick Training Topic” KTC TRAINING DEPARTMENT PRESENTS Diesel Engine Overhaul Section 4A Torque Wrench Primer

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    CDI Torque Products Industrial Training

    Presentsa Torque SeminarTorque Wrenches Care and Usage

    4A Torque Wrenches-*According to Webster -Torque: A twisting or wrenching effect exerted by a force acting at a distance on a body, equal to the force multiplied by the perpendicular distance between the line of action of the force and the center of rotation at which it is exerted.

    The definition of Torque In English PLEASE !!

    4A Torque Wrenches-*

    The formula for TorqueTorque is directly proportionate when figured at right angles.

    L x F = TLength times Force = Torque

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    A Torque exampleExample: A two foot lever at a right angle to the fastener with 200 pounds at the end will produce 400 foot/pounds of torque.

    L(ength) x F(orce)=T(orque)

    2 Length200 lbs. Force

    400 ft. lbs. of torque

    4A Torque Wrenches-*

    Torque UnitsTorque is expressed in both length and weight units. 1 ft. lb. = 12 in. lbs.1 in. lb. = 16 in. ozs.Units by which torque is measured can be converted to other units without actually changing the torque value.

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    Torque vs. Friction45%-55% to overcome friction of head surface.Only 10% of force is used to stretch bolt.35%-45% to overcome friction of threads.

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    When stretched, the fastener tries to maintain its original size.Internal tension is clamping force.Clamping force. (Pre-load)By the use of a fastener, were trying to make two pieces act as one.The greater the tension, the greater the clamping force.

    What are we trying to accomplish?

    4A Torque Wrenches-*

    If the clamping force of the fastener is greater than any outside force applied to the joint, then the bolt and the fastened items will remain as a single, solid unit. (No movement occurs in relationship to each other.)

    Clamping Force

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    Clamping ForceRepeated stretching and relaxing of the bolt can eventually cause metal fatigue and subsequent failure of the fastener.Vibration is common in many fastened joints. The stress, relax, stress, relax cycle repeated many times can cause an improperly tightened fastener to quickly fail.

    4A Torque Wrenches-*

    Torque Wrench Safety

    These precautions should always be taken when using any torque wrench to avoid possible injury:Read instruction manual completely before using torque wrench. Safety glasses or goggles should be worn at all times when using any hand tool.Always pull, DO NOT PUSH, to apply torque and adjust your stance to prevent a fall should something slip.

    4A Torque Wrenches-*

    Torque Wrench Safety

    A cheater bar should NEVER be used on a torque wrench to apply excess leverage.Do not use with sockets or fasteners showing wear or cracks.Ratchet mechanism may slip or break if dirty, mismatched or worn parts are used.Make sure direction lever is fully engaged.

    4A Torque Wrenches-*

    Torque Wrench UseShould never be used in excess of its capacity.Torque wrenches should be exercised several times before use.The wrench selected should be calibrated in the same torque units that are specified.The required torque value should be between 20-100% of the wrench capacity.Use of a cheater bar will result in an inaccurate reading and can possibly damage the wrench.

    4A Torque Wrenches-*

    Torque Wrench Use

    Always grip handle firmly in the center.Approach final torque slowly and evenly. Stop pulling immediately when torque is reached.Never use a click torque wrench to break fasteners loose.Should be cleaned and stored properly.Should always be stored at its lowest setting. Wrenches should be re-calibrated if dropped.

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    Proper Tightening Sequence When tightening bolts in a flange pattern, the proper tightening sequence is very important. When tightened in a criss-cross pattern as shown here, an even preload distribution is achieved.

    4A Torque Wrenches-*

    Torque Wrench SelectionClick type (Micrometer adjustable)Click type ( Pre-Set non-adjustable)Dial typeScrewdriver Electronic

    4A Torque Wrenches-*

    Torque Wrench SelectionItems to considerAdaptersType of wrenchAccuracy rangeConversion to other unitsCondition and lubricity of the fastener(s)Tools and Procedures

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    Affects of friction on a joint The torque must overcome the friction in the joint.

    The amount of friction must be taken into account when calculating torque values.

    1234

    1 Torque2 Head friction

    3 Thread friction4 Clamp load

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    Joint Rate Simulator This device is used in conjuntion with a tester to determine the torque output of a non-impact rotary tool. By stacking the belleville washers in set patterns, the joint rate simulator can simulate soft, medium or hard joints.

    4A Torque Wrenches-*

    The hard Joint

    Examples1 Hard material2 Soft material1211

    Hard Joint

    testingtorque (%)

    Angle ofrotation()All applications where youll find a hard material directly below the bolt, are called hard jointsThe Hard Joint

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    The Soft JointWhen there is a pliable material directly below the bolt, the application is called soft joint.

    Examples 1 Soft material2 Hard material

    112

    soft Joint

    testingtorque (%)

    Angle ofrotation()

    4A Torque Wrenches-*

    Affects of friction

    4A Torque Wrenches-*

    Saving weight and costSimilar load capacity

    1/23/8High tensible bolt, grade 8Standardbolt,grade 5

    4A Torque Wrenches-*

    Units

    1 ft. lb. = 12 in. lb.1 in. lb. = 16 in. oz1 Nm = 10 dNm1 dNm = 10 cNm1 mkg = 100 cmkgInternational System NmMetric mkgEnglish ft. lb.

    4A Torque Wrenches-*

    ISO 6789 Test RegulationsAccuracy shall be within the range of 20% to 100% of the maximum torque value of the wrench.

    Test points at 20%, 60%, 100%

    3 readings per test point in each direction

    4A Torque Wrenches-*Standard TorquesAll bolts and nuts in Kubota engines should be tightened to a specific torque.It the manual does not list the torque; use the standard torque chart below.

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    4A Torque Wrenches-*Torque Wrench PrimerA torque wrench accurately measures the torque or twisting force applied to a nut or bolt to tighten it properly. When used properly, a torque wrench can help avoid damaging the fastener or the parts with which the fastener interacts

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    4A Torque Wrenches-*Torque Wrench PrimerThree types of torque wrenches can be used: direct reading, dial and micro adjusting (signaling, click). The selection of the proper torque wrench is necessary to obtain correct readings. It is not uncommon to have at least two torque wrenches handy with different graduations, because torque wrenches are most accurate at their mid scale reading.

    4A Torque Wrenches-*Torque Wrench PrimerAll torque wrenches should be checked periodically for accuracy. Torque wrenches should be calibrated at least once a year, every 10,000 torques or sooner if they have been subjected to abnormal handling or storage, i.e., the micro adjusting (signaling, click) type must be stored with the scale set at zero for accuracy to be maintained.

    4A Torque Wrenches-*Torque Wrench PrimerConverting MeasurementsIt is very easy to convert from inch-pounds to foot-pounds by using a factor of 12. There is 12 inch-pounds for every foot-pound. If a foot-pound torque wrench is used for a bolt that requires 90 inch-pounds, the conversion would be attained by dividing the 90 inch-pounds by 12. This would be about 8 foot-pounds. But if your wrench ranges from 0-200 foot-pounds, this measurement would be far from the mid scale number and hence not very accurate. There is no easy way to convert to SAE from metric unless on the scale of the torque wrench. Be very careful when converting as mistakes can cause damage.

    4A Torque Wrenches-*Torque Wrench PrimerUse a Torque Wrench CarefullyMost torque wrenches are not "torque limiting" tools. They will not prevent you from applying more torque than set. Do not continue pulling on the wrench past the beam torque reading or the audible click on the micrometer type wrench. This is especially important for the lower torque settings. Learn how different amounts of torque's "feel," so you will reduce the possibility of damage and/or injury due to accidental over torquing.

  • *Types of Torque WrenchesDial Indicator TypeDirect Reading Beam TypeSignaling or Click Type

    4A Torque Wrenches-*Torque Wrench PrimerThis type of torque wrench uses a dial indicator as the measurement output device. It is highly accurate and often used in research and engineering applications. The user sets a indicator mark on the dial and torques to the mark. One advantage of this type of torque wrench is the ability to apply torque in both directions. When removing fasteners, it is good to determine the Breaking Torque or the point which the fastener begins to move. While not 100% accurate, this can give you an indication if the fastener is too tight or too loose. If the breaking torque is much higher or lower than specification this may be the clue of failure.

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    4A Torque Wrenches-*Torque Wrench PrimerWhen using this tool to apply torque to a fastener, the beam bends, while the pointer remains straight, indicating directly on the scale plate how much torque, in foot-pounds and Newton- meters, is being applied. When torque is released, the beam straightens and the pointer returns to zero. This torque wrench features an impact-resistant handle that concentrates the force you apply at a floating pivot point for greatest possible accuracy.

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    4A Torque Wrenches-*Torque Wrench PrimerA signaling or micro-adjusting type torque wrench indicates when the preset torque value has been reached by releasing the handle for a few degrees of free travel. This release or "give" normally accompanied by an audible "click" signal and tells the operator to stop applying pressure.

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    4A Torque Wrenches-*Torque Wrench PrimerThe signaling or micro-adjusting torque wrench is the most common torque wrench in use at equipment ships. When used improperly it can be the most inaccurate. Before using a torque wrench, read the operating instructions. Different brands of wrenches may have different procedures to follow. Use the following Key Points to assist you in getting the most accurate results from your torque wrench!

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    4A Torque Wrenches-*Torque Wrench PrimerSelecting the Right Torque Wrench1. All mechanical torque wrenches are calibrated from 20% to 100% of full scale, therefore, they should never be used below or above those limits.2. To determine which torque wrench capacity is best suited for an application, many factors must be considered. However, as a recommendation, use the torque wrench in the middle 50% of the overall capacity of the tool. This will result in longer tool life, ease of use by the operator and increased accuracy from the clicker type torque wrench. A torque wrench is most accurate in the mid-range of its scale. It is often necessary to have more than one torque wrench for the job to comply with the mid range rule.

    4A Torque Wrenches-*Torque Wrench Primer3. There are no user-serviceable parts inside the wrench. Disassembling the wrench or making any adjustments will result in the loss of accuracy and will void the warranty.4. If permanent marking of your wrench is absolutely necessary, mark only the scale plate, handle, or head... do not stamp. Defacing the beam in any way will affect accuracy or result in beam failure.5. A torque wrench is a precision instrument; handle and stored with care. Do not throw it around, hammer with it, or use it as a pry bar.6. The wrench is lubricated for life and should not be oiled. The only exception is the ratchet head that may be lubricated as needed for smooth operation.

  • *Torque Wrench PrimerBefore & After Using the Torque Wrench

    4A Torque Wrenches-*Torque Wrench Primer7. If the torque wrench has not been used or has been in storage for some time, exercise it a minimum of three times at 100% of full scale before use. Place a fastener in a vice and torque a bolt at 100% of its torque. This releases an internal lubricant to coat the internal working parts. If this is not done, the torque wrench may not be accurate!

    4A Torque Wrenches-*Torque Wrench Primer8. Keep the wrench at its lowest torque setting when not in use.9. Torque wrenches are designed for manual tightening of threaded fasteners only. Do not use the wrench as a nut breaker or for any other purpose.

    4A Torque Wrenches-*Torque Wrench Primer10. Threads on bolts, nuts, and other mating components should be clean and smooth. A lubricant applied to the threads and under the head of bolts will produce more accurate and consistent results.

    4A Torque Wrenches-*Torque Wrench Primer11. Never torque a fastener that is already tightened. Loosen it first, then retorque to the desired value. The same applies to fasteners that were accidentally over torqued.

  • *Torque Wrench PrimerUsing the Torque Wrench

    4A Torque Wrenches-*Torque Wrench Primer12. While applying torque, the wrench should be held ONLY BY THE GRIP.13. Never apply more torque than the maximum scale reading.14. Approach final torque slowly and evenly. A jerk of the wrench will cause over torquing even on a clicker type wrench!15. Do not use "cheater bars" (a piece of pipe placed over the hand grip).

    4A Torque Wrenches-*Torque Wrench Primer16. Over torqued or defective fasteners and sockets may suddenly break. Ratchets or plain drives that are improperly engaged, worn out, damaged, or over torqued may slip or break. To prevent injury, keep proper footing at all times. Do not use the wrenches in places from which you may slip or fall, or around rotating machinery.17. At high torque readings, if both hands are necessary to apply enough pressure to operate the wrench, hold the grip in one hand, and put the other hand on the top of the first hand, never on the wrench body.18. Turn the nut or bolt you are tightening with an even, steady pull, applying even pressure. As turning resistance increases, turn more slowly. For accuracy, the nut or bolt must be in motion when the final torque measurement is made.

    4A Torque Wrenches-*Torque Wrench Primer19. If, as you approach the final correct torque reading, you hear or feel a "popping" or "snapping" noise or sensation from the fastener, it could mean that the fastener is seizing or galling. Remove the fastener and check for foreign matter or burrs on the threads. Clean the threads if necessary. You may want to consider using an application of anti-gall lubricant. Simply removing and retorquing the fastener may suffice.

    4A Torque Wrenches-*Torque Wrench UseAttachmentsAt times, it is impossibleor impractical to use regular sockets, (a good example is when you are torquing a delivery valve on an injection pump), and a special attachment must be used. Such attachments change the calibration of the torque wrench, and it is necessary to calculate the correct torque settings using the formula at left. Note:Regular (concentric) socket extensions which extend directly under the drive head along the axis of the drive do not affect the calibration of the torque wrench.Handle extensions (a piece of pipe put onto the wrench to make torquing easier) SHOULD NOT BE USED under any circumstances. Their use will result in erroneous torque readings, and may damage the grip or the adjusting mechanism.

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    4A Torque Wrenches-*Torque Wrench UseUse the chart at left to convert to other units of measurement.

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    4A Torque Wrenches-*

    The End

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