Why are Spanners Necessary? Focusing on a Quick Mechanism That Changes Common Perceptions of Spanners

Among the hand tools used for motorcycle and car maintenance, the most basic yet perhaps least frequently used is the open-end wrench, or spanner. While it's easy to focus on its drawbacks once you're accustomed to ring spanners or socket wrenches, the spanner has its own purpose and is an indispensable part of any tool set. Here, we introduce an evolved spanner that eliminates the hassle of "re-fitting" – one of its weaknesses.

Let's Review the Weaknesses of Spanners

Ring spanners and socket wrenches contact the bolt or nut at six points. Furthermore, with a 12-point ring spanner, you can turn it continuously by rotating the grip just 30°, allowing for re-fitting.

At first glance, it seems like two opposite sides are in contact, but a spanner cannot be inserted or removed without a gap between it and the nut, so they are not in close contact. This means the force is applied at two points on opposite sides of the hexagonal head. Therefore, for the same torque, the stress applied to the contact points is three times greater than with a ring spanner or socket wrench, which can lead to damage to the corners.

When turning bolts or nuts for maintenance or part removal, there are several tool options: spanners, ring spanners, socket wrenches, and T-wrenches. Among these, it's likely that the spanner is the tool that even moderately experienced DIY mechanics might not reach for first.

There are several valid reasons why the spanner, which should be the most common tool in home center tool aisles and tool sets, is often overlooked.

Spanners have the following disadvantages:

1. Limited Contact Area

A standard spanner only grips two flat sides of a hexagon. This makes it prone to:

Stress concentration
Damage to bolt corners
Stripped nuts

These risks increase with higher tightening torque.

2. Not Suitable for High Torque

As the name "open-end" suggests, the end of a spanner is open. When force is applied in either the loosening or tightening direction, the opening tends to widen. This is called "mouth opening." As a result, you may encounter:

Tool slippage
Damage to the bolt

These problems can occur.

3. Requires Re-fitting

With a typical spanner, you repeat the cycle of: turn → remove → re-fit → turn.

This means that in tight spaces where there isn't enough room to swing the tool, frequent re-fitting is necessary.

In actual work, point 3 is often the biggest source of frustration. While ring spanners also require re-fitting unless you're in a situation where you can spin them like a propeller, a 12-point ring spanner only needs a 30° swing to be re-fitted. However, a spanner requires a 60° turn to move to the "next side." Offset spanners, which have an angled opening relative to the grip, allow you to turn a bolt with a 30° swing by flipping them over, but this still takes time.

In contrast, a 72-tooth ratchet handle can turn a socket with a 5° swing angle, making the difference in workability in tight spaces quite apparent.

Given these facts, it's realistic to say that there's no compelling reason to choose a spanner when a ring spanner or socket wrench can be used.

However, There Are Tasks Only Spanners Can Do

Spanners are useful in situations where ring spanners or socket wrenches absolutely cannot be used, such as for flare nuts on brake lines or nuts on stud bolts.

Although spanners require a larger swing angle than ring or socket wrenches and are not ideal for applying high torque, there are certain tasks where only a spanner can be used. These include:

1. Can be Inserted from the Side

While ring spanners and sockets must be inserted from above the bolt head or nut, a spanner can be inserted from the side. For example, in situations where pipes or bolts pass through the top and bottom of a nut, such as with:

Brake lines
Hydraulic lines
Nuts on stud bolts

only a spanner can be used.

2. Fits in Tight Spaces

Related to point 1, spanners also feature thin heads. In situations where the clearance above the bolt or nut is small and a ratchet handle would interfere, a spanner might still fit.

3. Quick to Engage

Unlike ring spanners or sockets, which need to fully enclose the hexagonal head of a bolt or nut, a spanner can be hooked on from the side. This can speed up work for initial tightening or low-torque applications. However, be cautious, as applying significant force with the opening only partially engaged can easily strip the corners of the bolt.

Thus, spanners have their place, and they won't be disappearing from toolboxes anytime soon.

A Quick Mechanism That Leverages Spanner Advantages While Compensating for Weaknesses

This is a swivel quick-release ratchet ring spanner from TONE, a comprehensive tool manufacturer.

The ring spanner also features a ratchet mechanism for quick turning. The direction of rotation is switched by flipping the tool over, rather than using a lever.

A movable claw on one jaw switches between gripping and releasing the hexagonal head based on the direction of rotation. This allows you to turn the bolt or nut without removing the spanner body. The opposite jaw also has a unique stepped design. When force is applied in the direction of the arrow on the jaw, it firmly holds the hexagonal head. When turned in the opposite direction, it rotates freely, allowing the grip to be swung back.

It's incredibly useful to be able to turn fasteners in tight spaces without having to remove and re-insert the spanner itself.

While ring spanners and socket wrenches may offer superior strength and ease of use, spanners have their advantages depending on the task. The significant weakness of spanners – the need to remove and re-fit the tool for every turn – has been addressed by the development of quick-mechanism spanners.

The origin of this concept is believed to be Snap-on's Speed Open-End wrench. This wrench featured a unique jaw shape that allowed continuous turning of bolts and nuts solely by swinging the grip, without needing to remove and re-fit it.

In contrast, later quick-mechanism spanners, such as the TONE Quick Spanner introduced here, feature a movable claw on one jaw that pivots around a fulcrum to grip and release the hexagonal head. This allows for continuous turning of bolts and nuts without removing the spanner body.

Additionally, this spanner has a unique stepped design on the jaw opposite the movable claw, which is another key to enabling continuous rapid turning without re-fitting.

While standard spanners can be used on either side for turning, this spanner has a fixed turning direction for both tightening and loosening due to the movable claw.

Furthermore, the claw incorporates a tension spring on its underside. This means that if dirt or debris, such as grit, gets caught in the mechanical parts when used on a dirty motorcycle, it could cause issues.

Nevertheless, the standard spanner's "turn → remove → re-fit → turn..." sequence is replaced by "turn → return → turn → return...", significantly reducing work time by eliminating the need to remove the tool.

In tight spaces, the stress of removing and re-fitting the tool is alleviated, and the reduced number of re-fits also lowers the risk of damaging bolt corners, which is a major benefit.

While they may only be used in specific situations during maintenance, these evolved spanners with quick mechanisms that enable continuous work without removing the tool are attractive tools for DIY mechanics aiming to improve their efficiency.

TONE's quick spanners are available in combination types with a ring spanner on one end, as well as standard spanner types. The ring spanner portion comes in swivel, straight (non-swivel), and lever-operated reversible types.