What Is a Ratchet Handle?
Ratchet handles are a type of socket wrench with a ratchet mechanism.
The ratchet mechanism refers to a gear that limits the direction of rotation in which force is applied in one direction. A familiar example is the pedal portion of a bicycle. When pedaling, force is applied, but when not pedaling, the cogwheel is spinning.
In the same way, when you want to tighten a screw, force is transmitted when the handle is turned clockwise, and when the handle is turned counterclockwise in the loosening direction, it is possible to spin the wheel. This eliminates the need to change the tool as the screw rotates when tightening/loosening the screw, making work much faster.
The direction of rotation in which force is applied can be easily switched using a lever, making it easy to switch between screw tightening and screw loosening operations.
Uses for Ratchet Handles
Ratchet handles are used for tightening and loosening screws. As the screw rotates, the tool can be continuously tightened or loosened without having to reapply the socket.
Normally, the tool must be removed from the screw each time the screw is rotated, and then inserted again from a different angle to tighten or loosen the screw over and over again. Depending on the pitch of the bolt, the bolt will only advance 1.5mm (or 1.25mm) per rotation, so if the bolt is 10mm long, it will require 6 to 7 rotations to remove the bolt.
This method requires a lot of work time in proportion to the length of the bolt. However, by using ratchet handles, the bolt can be rotated at high speed without having to remove the tool each time, thus significantly shortening the work time.
The direction of rotation for applying force to the ratchet mechanism can be easily switched between tightening and loosening with the lever. When using a socket wrench in a small workspace, it is necessary to pull out the socket once it reaches the full rotation angle of the handle and reapply it. With ratchet handles, on the other hand, you can simply turn the handle in the opposite direction to tighten and loosen it again.
Principle of Ratchet Handles
Inside the ratchet mechanism are a pawl and a gearwheel, which engage with each other to stop rotation. The pawl is pressed against the gear using spring force.
The relationship between the pawl and the gears is set up so that the pawl acts only in a certain direction, and rotation of the gears in the opposite direction pushes the pawl up and causes the gears to rotate. The “clicking” sound when the ratchet mechanism is turned in a direction where no force is applied is due to the pawl being pushed up and falling between the following gears.
By operating the lever to switch the direction of rotation, another pawl with a different pawl engagement direction engages the gear again, allowing for reverse rotation.
How to Select Ratchet Handles
1. Size
Size has different meanings in terms of the size of the socket insert and the size of the ratchet handles themselves. In general, there are three widely used socket sizes: 1/4 (6.35mm), 3/8 (9.5mm), and 1/2 (12.7mm).
The 3/8 (9.5mm) is neither too large nor too small and is easy to use, so this size is recommended at first.
The size of the ratchet handles themselves will increase in proportion to the size of the socket insert. Larger ratchet handles are stronger and can therefore apply higher torque. Some socket sizes are as small as a nail clipper, allowing them to be used in tight spaces without difficulty.
2. Locking Mechanism
If there is a lock mechanism, the socket cannot be removed without unlocking it, which makes it safe to work with. However, it is necessary to hold down the lock release button while removing and installing the socket, which increases the time and effort required if the socket needs to be removed and installed frequently.
Attempting to forcibly remove the socket without releasing the lock will result in damage to the ratchet handles, so the sockets must always be unlocked before being removed. Even if there is no lock mechanism, a simple anti-loosing mechanism called a ball plunger is provided, so a lock mechanism is not always necessary.