The following is a description of the difference between cheater bars and handle extensions adapted from the Ameren presentation they gave a couple of years ago at an American Gas Association meeting.
Pipe Wrench Handle Extenders Ameren Corporation is a large gas and electric utility in Illinois and Missouri. They have developed a handle extension for pipe wrenches in order to lower the amount of force required for wrenching. This is done by extending the length of the wrench which increases the moment arm so the same about of torque can be supplied by using less force. Using less force can help reduce injuries associated with wrenching. For example, you only have to use about half the force to create the same amount of torque using a 24 inch wrench instead of a 14 inch wrench. Why is the Ameren Pipe Wrench Extender not just a cheater bar?
Gas utilities are using three sizes of Handle Extenders for three sizes of pipe wrench: 14”, 18” and 24”. The handle extender increases the length of the handle of the wrench so that you can apply less force to achieve the same amount of torque. For example: To tighten a 1” fitting using these three wrenches requires a different amount of force: 14” wrench you need 64 lbs of force 18” wrench you need 52 lbs of force 24” wrench you need 37 lbs of force But using the handle extenders you can use much less force 14” wrench with 24” Handle Extender you need only 38 lbs of force 18” wrench with 30” Handle Extender you need only 31 lbs of force 24” wrench with 45” Handle Extender you need only 20 lbs of force That’s 64 lbs down to 38 lbs for a 14” wrench, 52 lbs down to 31 lbs for an 18” wrench, and 37 lbs down to 20 lbs of force for a 24” wrench. Other benefits of using the Handle Extender · The pipe wrench is pinned into position inside the handle extender so the pipe wrench can’t slip causing an injury. · The handle extender has a special non-slip grip so you can grip it more securely with less gripping force. This lowers fatigue for the muscles in your hand, which reduces the chance of injury. · The handle extender is sized properly to the wrench so you reduce the risk of breaking the wrench. A cheater bar can be too long, making it more likely you'll put too much stress on the wrench. · The handle extender is made of standard aluminum pipe with known strength, so it is designed to visibly bend before you break the wrench. It is the “weak link”. Proper Use 1) Make sure your pipe wrench is in good condition and the jaws are clean 2) Insert the pipe wrench into the proper handle extension and secure it with the “D-clip” pin 3) Grip the handle extension in the non-slip area for the best grip and to achieve the best leverage 4) Use your company’s recommended wrenching techniques Improper Use 1) Don’t hit the handle extension with a hammer or other tool or your hand, use a gradual steady pull or push 2) Don’t use the handle extension for non-approved tools, it is designed specifically for pipe wrenches 3) Don’t pound the extender onto the wrench handle, it should fit easily. For some brands of wrenches small adjustments may need to be made so the hole in the wrench meets the hole in the extender. You can do this by cutting a quarter inch or so off the end of the extender. The following specifications table was also in their presentation (For purchasing use the information chart at the end of this web page, not this one)  _______________________________________
As shown above, Ameren came up with these extenders to design a safer cheater bar to help reduce wrenching injuries. The idea is being broadly adopted because they reduce the forces on the body which reduces injury and fatigue. It should be noted that using any mechanical assist such as hitting the wrench with a hammer, or using a cheater bar will void the warranty on the wrench. Ameren did the design work and testing for 14" 18" and 24" aluminum pipe wrenches, but did not do the calculations for a 36" or 48" aluminum pipe wrench (they did it for steel wrenches). Two fabricators designed the 36" and 48" and they have been tested over 500 lbs. bending force with no permanent deformation of wrench or extender using high quality american made aluminum pipe wrenches. The pipe wrench handle extenders are a series of five aluminum pipes that are sized to fit 14", 18", 24", 36" and 48" aluminum pipe wrenches. They work with steel wrenches too. They have a pin to keep the wrench from falling out, and the pipe is made of aluminum so it will visibly bend when you're pulling too hard. The aluminum also makes them light weight. Finally, they have either a knurled or machine textured grip so your hands don't slip. The grip won't wear out, doesn't add to the diameter of the grip, and works well when you have wet muddy gloves. The 48 inch pipe wrench extender is only 12 lbs. and comes in two parts so it's easy to ship and store on your truck. There is a reasonable diameter for your grip, and then a big enough pipe for the wrench end. To fit the wrench snugly, the end of the extender is shaped, similar to what was done with the 36". Below you can see the 48" extender assembled and the two parts. Some of the retaining pin details were also changed.  Below is a photo of the whole range of extenders. . 
 The pin holds the wrench inside the handle so it won't slide out when in use.  And here's a close-up of the proprietary machine textured handle, and the knurled grip. You can get the knurl on all the sizes except the 36", and the machine textured grip on the 36". The two grip styles were tested grabbing the tools wearing wet leather gloves with a mix of snow and mud on the handles and they both performed well, so they are really interchangeable.  If you’re interested in more information or to purchase call me at 224 715 3699, email Bruce@ErgonomicToolDevelopment.com or you can buy them over the web at the sites listed below although it can be a little faster and less expensive if you just call or email me.
For those who want to purchase over the web all five sizes are on the Ionix site. For 14" wrench http://www.theionixgasstore.com/14piwrhaex1.html For 18" wrench http://www.theionixgasstore.com/18piwrhaex.html for 24" wrench http://www.theionixgasstore.com/24piwrhaex.html for 36" wrench http://www.theionixgasstore.com/36piwrhaex.html and for 48" wrench http://www.theionixgasstore.com/48piwrhaex.html Warranty; Limited Remedy; Limited Liability. This product will be free from defects in material and manufacture at the time of purchase. User assumes all risk. Bruce K. Campbell Consulting & Sales Inc. nor Bruce K. Campbell make no other warranties including, but not limited to, any implied warranty of merchantability or fitness for a particular purpose. If this product is defective within the warranty period stated above, your exclusive remedy shall be, at Bruce K. Campbell option, to replace or repair the product or refund the purchase price of the product. Except where prohibited by law, Bruce K. Campbell will not be liable for any indirect, special, incidental or consequential loss or damage arising from this product, regardless of the legal theory asserted. | ||||||||||||||||||||||||||||||