What Is a Geared Head Wrench?
A geared head wrench is a combination wrench (spanner on one side and a spectacle wrench on the other) with a ratchet mechanism gear attached to the spectacle wrench.
They are called variously by different manufacturers, such as combination gear wrenches, ratchet combination wrenches, and ratchet eyeglass wrenches.
Uses of Geared Head Wrenches
Geared head wrenches are used to tighten and loosen bolts and nuts. Specifically, they are used in a wide range of situations, including car and motorcycle maintenance, assembly of industrial machinery, equipment installation, and plumbing work.
In particular, they are often used for bolts and nuts located in deep and narrow places. Since the ratchet mechanism improves work speed, it is also useful at sites where productivity is required.
Principle of Geared Head Wrenches
The most distinctive feature of a geared head wrench is the ratchet mechanism attached to a spectacle wrench. The ratchet mechanism is a mechanism that transmits force in only one direction and rotates.
A familiar example of a ratchet mechanism is a bicycle pedal. Turning the pedal forward moves the bicycle forward, but turning the pedal in the opposite direction only causes it to spin, not backward.
When tightening a bolt with a standard eyeglass wrench, it is necessary to remove the eyeglass wrench from the bolt many times and then reinsert it. However, with a geared head wrench, force is transmitted only in the tightening direction, so continuous tightening work is possible. The work efficiency is dramatically improved by eliminating the need to re-fasten the bolt.
Also, the ratchet mechanism allows tightening work with a small swing. The standard eyeglass wrench is a 12-sided wrench, which requires a swing of 30° (360° ÷ 12). A geared head wrench with 72 gears, the most common type, requires only 5° of swing (360° ÷ 72). A smaller swing enables work in a smaller space.
How to Choose a Geared Head Wrench
There are four points to look for when selecting a geared head wrench:
1. Bolt Size
The most important factor to consider when selecting a geared head wrench is the bolt size. The most commonly used sizes are 8mm, 10mm, 12mm, 14mm, 17mm, and 19mm.
If you purchase a set, you need to make sure that it is a set of millimeter sizes. Inch sizes are also available, but millimeter size bolts are more commonly used.
2. Length of the Wrench
In addition to the regular type, there are two other types of geared head wrench handle lengths: long and short. Basically, the normal type can be used in many cases.
The long type is used in hard-to-reach places or when great force is required. The short type is necessary when the space is too small to turn the handle with the normal type.
3. Pivoting Type
There are two types of geared head wrenches: fixed type and pivoting type. Swivel type geared head wrenches are also called flex-type geared head wrenches.
The swivel type is very convenient because it can access bolts at an angle. If you are going to purchase one of these types, we recommend the swivel type because the fixed type cannot handle interfering objects.
However, the swivel type is difficult to apply force because it turns the bolt while holding the neck in place. The fixed type is superior in terms of work stability.
4. Number of Gears
The ratchet mechanism of a geared head wrench is usually 72 gears (5° feed angle). There are also products with 80 gears (4.5° feed angle), 90 gears (4° feed angle), 100 gears (3.6° feed angle), and 120 gears (3° feed angle). The higher the number of gears, the smaller the feed angle and the easier it is to work in tight spaces.
Please note that some geared head wrenches with less than 72 gears cannot be tightened, while most geared head wrenches with 72 or more gears can be tightened.