Ko-ken Z-Series: High Torque, Low Profile Ratchets with the Smoothest Back Drag

The competition either has a decent back drag or high torque, but not both, at least as balanced as the Z-series from Ko-ken.

Let’s visually analyze the internal mechanism of some competitors against the Z-series to understand its superiority better.

Most ratchets include springs in their internal mechanism. However, the ratchet from the above image has large springs that produce a high back drag. I mean, look at the size of those springs.

As discussed in our article about heavy equipment track adjusters, compressed springs store potential energy called “restoring force.” The restoring force increases according to the spring size.

The next ratchet has one of the most complicated mechanisms we’ve seen. Its design makes it a pain to reassemble when servicing the ratchet and increases the cost of the manufacturing process.

The combination of several teeth engaging while back-dragging, pawl friction, and a W-shaped spring contributes to the ratchet’s high backlash.

The flaw with the model above is the fixed spring position. When the bottom of the pawl reaches the spring, it does so in an awkward position, making it hard to compress it.

Think about it this way. When you press a button, you push it straight down instead of sliding your finger over it, which would be harder and awkward.

The balance between low back drag and high torque of the Z-series comes from the combination of the following features:

• A dual pawl system: the lower pawl pivots while the upper one “floats” on top. The system allows only one tooth to engage while back dragging (minimizing resistance) and quickly engages all teeth when torquing.
• The spring pivots to a position where the lower pawl generates the maximum compressive force on the spring by pressing it straight down, significantly reducing the effort to back drag.
• Ko-ken even tested several spring pressures to maintain their hallmark low-torque backlash.

Don’t take our word for granted yet. Check the following videos from Tool Demos and Project Farm to verify what we’ve claimed:

• Moving a Koken ratchet by blowing air.
• Third place out of a list of 16 tested ratchets.

While most manufacturers have accepted movement at the joint between a socket and a ratchet as unavoidable, Ko-ken used new technologies in its production processes to minimize tolerances across flats at the drive and head sockets.

The smaller tolerances and the new Ball Holding System significantly reduce movement in the rotating and connecting directions.

Reducing the floppiness at the joint matters, especially when working in tight spaces. Ideally, the bolt should move as soon as you rotate the ratchet.

Too much tolerance will cause a slight delay, which might not seem much unless you try to tighten several bolts within shallow-degree working angles, and instead of doing 20 passes with the ratchet for each, you do 40.

The slight delay will start to add up, making things more time-consuming, and for a mechanic, time is money.