Q: WHY IS APPLYING PROPER TORQUE IMPORTANT? A: C reating proper Clamp Load prevents damage and equipment failures. • Safety & Performance: Applying accurate torque is critical to assembly applications, engines and precision equipment. • Creating a proper clamp load is the main objective when applying torque to a fastener. Engine cylinder heads, pipe coupling, wheels, all need to be “clamped” uniformly to specific torque values. • There are three main factors that affect the correct application of torque: (1) Condition of components, (2) Accuracy of torque instrument, (3) Properly applied torque values. • Applying torque incorrectly can lead to stripped threads, premature loosening or broken fasteners that can cause catastrophic failure. Leaking joints may cause engine or equipment failures. Q: WHAT IS TORQUE? A: Torque is rotational or turning force. Torque is measured in length and force: Length means distance from “center of drive” to “center of handle". Force means “pounds”, “Newtons” etc. Q: WHAT IS A TORQUE INSTRUMENT AND WHAT DOES IT DO? A: Any device that applies a pre-determined amount of torque to a fastener. • It may be mechanical or electronic in design. • A torque wrench has some type of indicating device which lets the operator know when the correct torque has been achieved: “click” or “impulse- break” feel; sound; lights; gauge; or some combination of these. MICROMETER (CLICK TYPE) The most popular type of mechanical torque wrench. An internal spring is tightened by turning the handle. The spring pushes against a block, and both are calibrated so the block pivots when the torque setting is reached. This quick pivoting creates the "click" sound. When the force at the handle is released, the block resets to it's original ® position and is ready for the next torque application. SPLIT BEAM (QUICK ADJUST) Also called a "Quick Adjust" wrench, this type is most popular for automotive tire and wheel installation and other heavy use environments. Torque value is set by turning a small knob on the side of the wrench. Two internal arms (the "split beam") bend when force is applied at the handle, and a trigger device reacts when the set ® torque is reached, causing a "click" that can be felt and heard. Q: HOW DO YOU CALCULATE TORQUE? A: Torque = Length × Force The standard torque formula used to calculate torque is: “L x F = T" Example: 2 ft. (length) x 30 lbs. (amount of force at center of handle) = 60 ft. lbs. of torque (60 Ft. Lbs.) TORQUE (Turning Force) FORCE (Pressure Applied) LENGTH (Distance from pivot point to force) ® Q: WHAT DOES TORQUE DO? HEAD FRICTION 45% of Applied Torque THREAD FRICTION Up to 45% of Applied A: Torque creates a "Clamp Load" to join two pieces of ® material. • B olts (or threaded fa ® steners), are designed to create clamping force, also called “clamp load”. • When torque is applie 3 d 40 to 350 a 0 th 10 re 20 aded fastener, 330 30 it draws together t 32 h 0 e joint, (two piec 40 es of 310 50 300 Torque material). 250 260 270 280 290 60 70 80 90 100 110 120 • A s additional torque is applied to the fastener, the joint is pulled together creating a clamp load as the fastener begins the stretching process. It’s this fastener stretch that creates 240 and maintains clamping force, like a stretched 230 130 140 bungee cord maintaining tension. 220 150 160 170 180 190 200 210 • The actual amount of clamp load is determined by several factors: – The amount of torque applied to the fastener. BOLT STRETCH – The material and grade of the fastener. 10% of Applied LOAD – The external friction on the joint – friction Torque Distributed over under the fastener head, and friction between all threads the threads of the fastener and material it’s connected to. Q: WHAT IS TORQUE PLUS ANGLE? A: Torque Plus Angle creates a more exact clamp load for torque-sensitive equipment. Auto manufacturers and makers of other high performance equipment are increasingly specifying fasteners with a combination of torque value followed by additional tightening with “angle”, or degrees of wrench turn. Manufacturers can calculate a more exact final “clamp load” for their applications, since “torque & angle” minimizes the impact of thread or under-head friction. 340 350 0 10 20 330 30 320 40 310 50 300 250 260 270 280 290 60 70 80 90 100 110 120 240 230 130 140 220 150 160 170 180 190 200 210 EXAMPLE Apply 80 ft. lbs. of torque, then apply 90 degrees of rotation 250 260 270 280 290 240 300 230 310 ® ® MECHANICAL DIAL Uses a fixed, non-ratcheting square drive. Available in single scale and dual scale models. As force is applied at the handle, an internal beam flexes against a precision movement which rotates a needle pointing to the torque value 35 a 0 g 0 ai 1 n 0 st the dial scale. A m 330 e 3 m 40 ory 20 needl 3 e 0 i 4 ndicates the 320 0 50 highest torque value achieved. ® DIGITAL DIAL More accurate, easier to use and read than a mechanical dial because of large LCD readout and color LED light bar. Utilizes an internal electronic strain gage to measure torque. Uses a fixed, non-ratcheting square drive as do the mechanical dial wrenches. The strain gage positioning on the torsion drive allows this instrument to be non-length sensitive. 60 70 80 90 100 110 120 ® 130 140 220 250 260 270 280 290 ® 150 160 170 180 190 200 210 340 350 0 10 20 330 30 ELECTR 32 O 0 NIC 40 310 Most versatile and accurate 300 torque wrench. Operates by means of a internal electronic strain gage with digital readout. Torque value setting can be heard (beep) felt and seen (digital screen and lights). Snap-on TechAngle models enable fast and easy application of desired 240 torque, plus additional angle 230 application through internal Gyro 220 chip which measures up to 360 degrees of rotation. 140 130 50 60 70 80 90 100 110 120 TORQUE SCREWDRIVERS Used for applying torque in low torque applications, such as electronic assembly manufacturing, medical devices, etc. The cam-over design prevents over-torquing. Ergonomic tri- lobe handle design. Available in adjustable models, or factory preset to a single torque value. 150 160 170 180 190 200 210 U.S. Patents Snap-on has always been at the forefront of tool innovation, and torque products is no exception. Illustrated here are the US Patent numbers granted to Snap-on for the Control Tech & TechAngle models. U.S. Patent No. Model 9156148 Control Tech & TechAngle 9242356 / 9839997 Control Tech & TechAngle 9395257 Control Tech & TechAngle 9523618 Control Tech D699531 Control Tech D702519 TechAngle 2
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