There are two types of air torque tools. The first has a relatively low torque output and is suitable for light duty joints and assemblies. These are not technically air torque wrenches, but rather what are known as "air torque screwdrivers". A pneumatic screwdriver keeps the drive shaft engaged at all times. When the specified torque limit is reached, the clutch disconnects power to prevent overtorque. In manufacturing environments where every product needs to be tightened to exact specifications, air screwdrivers excel—at least when torque values are relatively low and are measured in inch pounds (lbf.in) rather than foot pounds (lbf.in) Correct in light assembly. feet).
Heavy-duty manufacturing environments require similar high-speed output, but higher torque values. In these environments, the best pneumatic torque wrench for the job is actually an impulse tool. Like air screwdrivers, they provide stable torque control through a gear mechanism. However, they are capable of higher levels of torque—over 330 lb-ft, while the maximum torque for an air screwdriver is about 95 lb-ft. If it weren't for the unique mechanism that helped give the pulse tool its name, that would have been enough to cause employee injuries from high-torque downtime responses.
Inside the pulse tool is the hydraulic mechanism between the drive shaft and the air motor. This mechanism allows the drive shaft of the tool to rotate freely when the fastener is loose. As the fastener gets tighter, the hydraulic pressure in the mechanism increases until it acts on the inner anvil, creating a force. The force reduces the hydraulic pressure inside the mechanism, but it immediately starts to increase again. This is the pulse action named for the pulse tool.
Impulse is similar to the effect of an impact wrench in that it isolates the user from kickback caused by high torque values. The difference is that the drive shaft is always engaged, allowing precise torque control. Pulse tools can automatically shut down when a specified torque value is reached, or do not allow the operator more control over tightening. The best air torque wrench for manufacturing would be one of those pulse tools or air screwdrivers that have the form and function for your tightening needs.