By Jonathan Peace
How Does a Power Ratchet Work?
Power ratchets are incredibly useful, time-saving tools. If you frequently use power ratchet wrenches, it’s helpful to understand how they work so that you can choose the right power ratchet for your specific needs.
You might think the tool runs in two directions: forward for tightening, reverse for loosening. But that’s not actually the case. Both pneumatic and cordless power ratchets run at a high RPM and in just one direction only.
The output of the motor goes through gearing, which reduces the speed and increases the torque, typically by a gear ratio of between 4:1 and 6:1. This drives a crankshaft with an offset pin on the end of it. This pin, in turn, swings a yoke that is constrained to only move from side to side. One complete turn of the crankshaft swings the yoke from one side to the other and back again.
Power Ratchet vs. Manual Ratchet
If this sounds confusing, picture a manual ratchet. You repeatedly swing the handle back and forth to move the socket. The yoke is doing the same thing, just with a short angular stroke and at a much faster rate.
The inside diameter of the yoke is lined with gear teeth that surround and interact with a pawl-based ratcheting mechanism, much like in a manual ratchet. When the yoke swings from one side to the other, the teeth lock with the pawl to turn the tool output. Then when the yoke swings back, the teeth slip past the pawl without any movement of the tool output.
The forward/reverse selector on the tool is used to change the orientation of the pawl so that it either locks with the yoke teeth for clockwise rotation of the tool output or for counterclockwise rotation.
If we return to the comparison with a manual ratchet, you’ll see the immense value in a power ratchet. Remember, one rotation of the crankshaft corresponds to one back-and-forth swing on the manual ratchet. How many times could you go back and forth in one minute?
Some of our power ratchets run at 24,000 RPM unloaded. The motor output goes through planetary gearing that has a gear ratio of 4.75, so that means that the crankshaft rotates at about 5,000 RPM (24,000 RPM divided by 4.75). One rotation of the crankshaft corresponds to one back-and-forth swing of the yoke, so that means the yoke is swinging 5,000 times per minute! One swing of the yoke moves the tool output 20 degrees, so that means that the tool output is rotating at approximately 280 RPM (5,000 swings per minute x 20 degrees per swing x 1 revolution per 360 degrees).
Which Power Ratchet Is Best for You?
Now that we understand more about how power ratchets work, let’s look at putting all that power to good use. More power is great, but sometimes you really care more about torque and control. So, our ratchets are configured in different ways for different jobs.
Ingersol Rand’s cordless ratchets give you the convenience of cordless with the power of air. They operate at 225 RPM and deliver up to 54 ft lbs. of torque. This makes them ideal for engine repair, under-car work, light industrial maintenance, and repair & operations (MRO).
Our 109XPA and 1099XPA high-torque pneumatic ratchet wrenches generally operate around 220 RPM and can deliver up to 76 ft-lbs. of torque while the 1211MAX High Speed Ratchet has a higher breakaway torque of 80 ft-lbs. and operates up to 625 RPM. The higher torque can be helpful to break stubborn bolts, for jobs where you need more control, or for use in tight areas where precision is key.
Check out Ingersoll Rand’s full line of ratchet wrenches to find the best wrench for your specific job.