GB2103977A - Spanner - Google Patents

Abstract

The handling of a ratchet spanner consisting of handle (1), drive dog (3) and socket (2) is improved by the provision of a flywheel (4) on the drive dog between handle and socket. Such ratchet spanners are useful for tightening clamping screws for plate clamping bars in offset printing presses. The flywheel mass enables bolts to be turned quickly through several revolutions. <IMAGE>

Description

SPECIFICATION Ratchet spanners This invention relates to ratchet spanners.

In many offset printing presses, plate clamping bars are arranged in a recess in a plate cylinder, the bars consisting of a bottom part and a top part, which can be pressed against the bottom part. The movement of the top part is effected by clamping screws, which carry the top part along when they are screwed into the bottom part and press it against the latter.

To clamp a printing plate, it is pushed between the top and bottom parts and clamped by tightening the clamping screws. For this purpose the printer or setter uses suitable tools such as ring, open-ended or box spanners. Ratchet spanners, which are more versatile than these types of spanner, because they can also be used at points of the machine not easily accessible, can be used, but the disadvantage of using a ratchet spanner is that it is not easy to work with it especially when clamping printing plates, because it cannot be handled like a box spanner.

According to the present invention there is provided a ratchet spanner consisting of a handle, a drive dog set in the handle for rotation via a ratchet relative thereto, and a drive member set on the drive dog and having a nut-engaging formation, wherein a flywheel is provided on the drive dog between the handle and the drive member. Such a spanner can be used to screw the clamping screws of a plate clamping bar while retaining handling advantages like those of the box spanner. The interposition of the flywheel mass between the handle and nut enables faster turning of the clamping screws, thus saving expensive setting time.

The invention is explained in more detail below with reference to a specific embodiment which is shown, in the accompanying drawing, and which shows one way in which the invention may be put to use.

Referring to the drawing, the ratchet spanner consists of a handle 1 in which is rotatably mounted, via a ratchet, a square drive dog 3, which permits slackening or tightening of bolts, screws or nuts according to its motion, via a socket 2 fitted on its end in known fashion. In accordance with the invention a flywheel mass in the form of a disc-type flywheel 4 is provided between the handle 1 and the socket 2. This disctype flywheel 4 has a central opening fitting over the square drive dog 3.

To slacken or tighten screws, bolts or nuts the disc-type flywheel 4 can then be turned by hand. The flywheel mass of the disc-type flywheel 4 is chosen such that the ratchet of the ratchet spanner can be overcome by a quick flick of the handle, which imparts sufficient inertia to the flywheel so that the screw or nut can be turned several times. Final tightening is then effected with the ratchet spanner used in the normal way.

1. A ratchet spanner consisting of a handle, a drive dog set in the handle for rotation via a ratchet relative thereto, and a drive member set on the drive dog and having a nut-engaging formation, wherein a flywheel is provided on the drive dog between the handle and the drive member.

2. A ratchet spanner according to claim 1 wherein the flywheel is a circular disc.

3. A ratchet spanner according to claim 2 wherein the material of the disc is concentrated at its outer edge.

4. A ratchet spanner substantially as hereinbefore described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Ratchet spanners This invention relates to ratchet spanners. In many offset printing presses, plate clamping bars are arranged in a recess in a plate cylinder, the bars consisting of a bottom part and a top part, which can be pressed against the bottom part. The movement of the top part is effected by clamping screws, which carry the top part along when they are screwed into the bottom part and press it against the latter. To clamp a printing plate, it is pushed between the top and bottom parts and clamped by tightening the clamping screws. For this purpose the printer or setter uses suitable tools such as ring, open-ended or box spanners. Ratchet spanners, which are more versatile than these types of spanner, because they can also be used at points of the machine not easily accessible, can be used, but the disadvantage of using a ratchet spanner is that it is not easy to work with it especially when clamping printing plates, because it cannot be handled like a box spanner. According to the present invention there is provided a ratchet spanner consisting of a handle, a drive dog set in the handle for rotation via a ratchet relative thereto, and a drive member set on the drive dog and having a nut-engaging formation, wherein a flywheel is provided on the drive dog between the handle and the drive member. Such a spanner can be used to screw the clamping screws of a plate clamping bar while retaining handling advantages like those of the box spanner. The interposition of the flywheel mass between the handle and nut enables faster turning of the clamping screws, thus saving expensive setting time. The invention is explained in more detail below with reference to a specific embodiment which is shown, in the accompanying drawing, and which shows one way in which the invention may be put to use. Referring to the drawing, the ratchet spanner consists of a handle 1 in which is rotatably mounted, via a ratchet, a square drive dog 3, which permits slackening or tightening of bolts, screws or nuts according to its motion, via a socket 2 fitted on its end in known fashion. In accordance with the invention a flywheel mass in the form of a disc-type flywheel 4 is provided between the handle 1 and the socket 2. This disctype flywheel 4 has a central opening fitting over the square drive dog 3. To slacken or tighten screws, bolts or nuts the disc-type flywheel 4 can then be turned by hand. The flywheel mass of the disc-type flywheel 4 is chosen such that the ratchet of the ratchet spanner can be overcome by a quick flick of the handle, which imparts sufficient inertia to the flywheel so that the screw or nut can be turned several times. Final tightening is then effected with the ratchet spanner used in the normal way. CLAIMS

1. A ratchet spanner consisting of a handle, a drive dog set in the handle for rotation via a ratchet relative thereto, and a drive member set on the drive dog and having a nut-engaging formation, wherein a flywheel is provided on the drive dog between the handle and the drive member.

2. A ratchet spanner according to claim 1 wherein the flywheel is a circular disc.

3. A ratchet spanner according to claim 2 wherein the material of the disc is concentrated at its outer edge.

4. A ratchet spanner substantially as hereinbefore described with reference to the accompanying drawings.