Patent Description:
A motor grader shapes or levels the ground by forcing a tool, such as a blade, to bear against the ground over which it is driven. For some applications, the grader is configured with a series of bits instead of a blade to better cut and break up the ground. For this configuration, the blade is replaced with an adapter board securing a plurality of bits.

Some bits are optimized for use in a forward-facing orientation. For example, they may have multiple tooling surfaces optimized to cut and shape the ground when the bit is maintained in a forward-facing orientation. The tooling surfaces may be made from a hard material, such as carbide, greatly reducing the tooling surface's wear rate and thereby increasing the bit's effective life. If such a bit is allowed to freely rotate, however, the other, non-tooling surfaces of the bit contact the ground, wearing the bit out far faster than when it is maintained in a forward-facing orientation.

Adapter boards of motor graders are generally designed to constrain the bits against rotation. For example, the underside of the adapter board may have a series of machined slots interlocking with the bits. Alternatively, a plurality of holes or slots in the adapter board may have non-circular cross-sectional shapes. For example, the slots may have rectangular or square cross sections. The bits may have corresponding non-circular shanks, such that once the shanks are received within a respective hole or slot in the adapter board, they are secured in a forward-facing orientation. Snap rings may be configured to attach to the bits to prevent them from falling out of the hole or slot in the adapter board.

The machined slots on the underside of the adapter board described above may help prevent rotation of the bits, but they may become worn as the underside of the adapter board scrapes and grinds against the ground. Once the machined slots have been completely worn away, they may fail to prevent rotation of the bits. Additionally, snap ring require specialized tools to remove, increasing the difficulty associated with removing and replacing the bits.

One exemplary system for securing bits in a forward-facing orientation is described in <CIT>. The shank of the bit, which is received within the holding device, has a rectangular cross section. The holding device has a complementary shaped slot for receiving the shank. To prevent the bit from falling out, a spigot and socket is provided.

Although the system of the '<NUM> patent may help secure bits against rotation, machining non-circular slots is generally more costly and time consuming than drilling circular holes. Additionally, the spigot-and-socket configuration involves small, intricate parts, increasing both manufacturing cost and installation difficulty.

The disclosed system is directed to overcoming one or more of the problems set forth above and/or other problems of the prior art.

<CIT> discloses a blade assembly for hard earth road graders having a support frame for attachment to the mouldboard of the road grader and a plurality of evenly spaced picks located in sockets spaced along the lower edge of the support frame. The picks have spigots to releasably locate in the support frame sockets and engage with the support frame to prevent relative rotation between the spigots of the picks and respective sockets. The picks each have a tungsten carbide tile attached to their front face with a straight transverse cutting edge along the lower edge. In use the working face of the picks is perpendicular to a road surface to achieve a shaving action.

<CIT> discloses a degradation pick of the type used in such fields as road milling, mining, and trenching to engage and degrade tough materials such as asphalt, concrete, and rock may comprise a body attached at one end to a substantially cylindrical shaft. A hardened tip may also be attached to the body opposite the shaft. The hardened tip may comprise an axis offset from a central axis of the shaft. Such a degradation pick may be secured to an exterior of a rotatable drum or continuous chain so as to be repeatedly brought into contact with a surface of a material to be degraded. The body may comprise a protruding spine adjacent the hardened tip and opposite a direction of travel of the hardened tip when transported by a rotating drum or continuous chain.

<CIT> discloses a landscaping attachment. The landscaping attachment is an earthworking or cultivating implement configured for towing behind a relatively small vehicle, e.g., a small all-terrain vehicle or garden tractor. The attachment includes adjustably positionable wheels which may be lowered to lift the implement above the surface, or lifted to place the implement on the surface. Wheel operation is by electric power. The wheels may be optionally positioned or relocated to the front or rear of the implement. The implement may comprise an I-beam scraper having a series of teeth cut into the front flange. Alternatively, the teeth may be individually replaceable units. The implement may include angularly adjustable wings extending from each end thereof. <CIT> discloses another example of a bit securing system.

In one aspect, the present disclosure is directed to a bit securing system, according to claim <NUM>. The bit securing system includes at least two bits, and each bit includes a respective shank. Each shank includes a respective locking portion. The bit securing system includes an adapter board having at least two holes, and each respective hole of the adapter board is configured to receive a shank of a respective bit. An anti-rotation plate is configured to engage the respective locking portions of the shanks of at least two bits such that the anti-rotation plate constrains them against rotation with respect to the adapter board.

In another aspect, which does not fall within the scope of the claims, the present disclosure is directed to another bit securing system. The bit securing system includes an adapter board having a hole therein. The bit securing system includes a bit having a shank, and the shank has a circular portion and a locking portion. The circular portion is configured to be received within the hole of the adapter board, and the locking portion has a non-circular cross-sectional shape. The bit securing system includes a first anti-rotation plate. The first anti-rotation plate is configured to engage the non-circular cross-sectional shape of the locking portion such that the first anti-rotation plate constrains the shank against rotation with respect to the adapter board.

In another aspect, which does not fall within the scope of the claims, the present disclosure is directed to another bit securing system. The bit securing system includes a bit having a shank. The shank has an end with a non-circular cross-sectional shape. The bit securing system includes an adapter board having a hole configured to receive the shank of the bit therein. The bit securing system includes an anti-rotation plate configured to contact one or more of an adjacent anti-rotation plate, a second bit, and an interference surface of the adapter board such that the anti-rotation plate is constrained against rotation with respect to the adapter board. The anti-rotation plate is configured to engage the non-circular cross-sectional shape of the shank such that the anti-rotation plate constrains the shank against rotation with respect to the anti-rotation plate.

<FIG> illustrates one embodiment of the system <NUM> for securing bits <NUM> against rotation. In this embodiment, the system <NUM> includes at least two bits <NUM>. Each bit <NUM> has a tooling surface <NUM>, and is designed to operate facing a forward direction <NUM>, as shown. An adapter board <NUM> secures the bits <NUM> such that the tooling surfaces <NUM> are facing the forward direction <NUM>. The adapter board <NUM> includes at least two bit holes <NUM>, and each bit <NUM> is removably received within a respective bit hole <NUM> in the adapter board <NUM>. The bits <NUM> are inserted into the bit holes <NUM> from a lower surface <NUM> of the adapter board <NUM>. An anti-rotation plate <NUM> is then positioned on an upper surface <NUM> of the adapter board <NUM> such that it engages with the bits <NUM> to constrain the bits <NUM> against rotation. The adapter board <NUM> also has an interference surface <NUM> extending from the upper surface <NUM>, and the interference surface <NUM> has a plurality of mounting points <NUM> configured to mount the adapter board <NUM> to the motor grader.

Each anti-rotation plate <NUM> is constrained against rotation with respect to the adapter board <NUM> by engaging at least two bits <NUM>. The anti-rotation plate <NUM> may be configured to engage any suitable number of bits <NUM>, however. As shown in <FIG>, each anti-rotation plate <NUM> may engage three bits <NUM>. Alternatively, each anti-rotation plate <NUM> may engage five bits <NUM>, for example.

<FIG> illustrates a second embodiment of the bit securing system <NUM>. Unlike the embodiment illustrated in <FIG>, a separate anti-rotation plate <NUM> is provided for each bit <NUM>. Each anti-rotation plate <NUM> engages with one respective bit <NUM> to constrain it against rotation. Each anti-rotation plate <NUM> also abuts one or more of the interference surface <NUM> of the adapter board <NUM> and the adjacent anti-rotation plate <NUM> such that the anti-rotation plate <NUM> is constrained against rotation with respect to the adapter board <NUM>.

The bit holes <NUM> may be formed between the lower surface <NUM> and the upper surface <NUM> of the adapter board <NUM>. The circular portion <NUM> of the shank <NUM> may be sized such that when the system <NUM> is assembled, the shoulder <NUM> of the bit <NUM> contacts the lower surface <NUM> of the adapter board <NUM>. When assembled, a locking portion <NUM> of the shank <NUM> extends at least partially outside of the bit hole <NUM> of the adapter board <NUM> from the upper surface <NUM>. The anti-rotation plate <NUM> is then positioned on the upper surface <NUM> of the adapter board <NUM> such that the slot <NUM> in the anti-rotation plate <NUM> receives the locking portion <NUM> of a respective shank <NUM>. Additionally, in some embodiments, the locking portion <NUM> of the bit <NUM> may be sized such that the locking portion <NUM> is at least partially received within the bit hole <NUM> in the adapter board <NUM> when the system <NUM> is assembled. In other words, the locking portion <NUM> may be disposed at least partially within the bit hole <NUM> in the assembled state.

<FIG> illustrates an exemplary bit <NUM> according to the embodiment illustrated in <FIG>. The bit <NUM> has a shoulder <NUM> and a shank <NUM> protruding from the shoulder <NUM>. The shank <NUM> includes a circular portion <NUM>, the locking portion <NUM>, and an end <NUM>. The locking portion <NUM> is disposed at the end <NUM> of the shank <NUM>, and the circular portion <NUM> is disposed between the locking portion <NUM> and the shoulder <NUM>. The circular portion <NUM> has a circular cross-sectional shape, and the locking portion <NUM> has a non-circular cross-sectional shape. In this embodiment, the locking portion <NUM> has a pair of flat, parallel engagement surfaces <NUM>.

The locking portion <NUM>, however, may have any suitable non-circular cross-sectional shape such that the anti-rotation plate <NUM> can engage the locking portion <NUM> when the system <NUM> is assembled and constrain the bit <NUM> against rotation. For example, in other embodiments, the engagement surface <NUM> may be curved. In other embodiments, the locking portion <NUM> may only have one engagement surface <NUM>. Alternatively, the locking portion <NUM> may have more than two engagement surfaces <NUM>. For example, multiple engagement surfaces <NUM> may define a cross-sectional shape of the locking portion <NUM> that is triangular, square, rectangular, or pentagonal, etc..

The engagement surface <NUM> may be formed using any suitable method known in the art. For example, the engagement surface <NUM> may be formed by removing material from the shank <NUM>. When first formed, the shank <NUM> may have a circular cross section along its entire length. One or more engagement surfaces <NUM> may then be formed by removing a portion of the shank <NUM> using any suitable technique. For example, the shank <NUM> may be machined, ground, cut, etched etc. to form one or more engagement surfaces <NUM> in the locking portion <NUM>. Any other suitable manufacturing technique may be used to form a locking portion <NUM> having a non-circular cross sectional area. For example, the bit <NUM> may be cast using a mold. Alternatively, various portions of the bit <NUM> may be formed separately and welded together.

<FIG> illustrates one possible configuration for the locking portion <NUM> of the shank <NUM>. Two parallel engagement surfaces <NUM> are disposed at a <NUM> degree angle with respect to the forward direction <NUM>. The engagement surfaces <NUM> may be oriented in any suitable direction, however. For example, in the embodiment illustrated in <FIG>, the engagement surfaces <NUM> are disposed perpendicular to the forward direction <NUM>.

The circular portion <NUM> is configured to be received within a respective bit hole <NUM> of the adapter board <NUM>. For example, both the circular portion <NUM> of the shank <NUM> and the bit holes <NUM> of the adapter board <NUM> may be sized such that circular portion <NUM> can be easily inserted and removed from a respective bit hole <NUM>. For example, the circular portion <NUM> of the shank <NUM> and the bit holes <NUM> of the adapter board <NUM> may form a sliding or running fit.

The anti-rotation plate <NUM> of the embodiment illustrated in <FIG> is illustrated in <FIG>. The anti-rotation plate <NUM> includes a slot <NUM> configured to engage the non-circular cross-sectional shape of the locking portion <NUM> of the shank <NUM>. In this embodiment, the slot <NUM> is configured to interlock with the non-circular cross-sectional shape of a respective locking portion <NUM> of each shank <NUM>. The slot <NUM> includes a shape that is complementary with respect to the non-circular cross-sectional shape of the locking portion <NUM> of the shank <NUM>. The inner edge <NUM> of the anti-rotation plate <NUM>, which forms the slot <NUM>, has at least one surface configured to interfere with the engagement surface <NUM> of the locking portion <NUM> when the system <NUM> is assembled. In other words, the inner edge <NUM> of the anti-rotation plate <NUM> contacts the engagement surface <NUM> of the locking portion <NUM> of the shank <NUM> such that the bit <NUM> is constrained against rotation. To form the slot <NUM> in the anti-rotation plate <NUM>, any suitable technique may be used. For example, the slot <NUM> may be machined, cut, punched, etc. Alternatively, the anti-rotation plate <NUM> may be cast in a mold, for example.

When the anti-rotation plate <NUM> is installed as shown in <FIG>, an outer edge <NUM> of the anti-rotation plate <NUM> interferes with the outer edge <NUM> of an adjacent anti-rotation plate <NUM>. The outer edge <NUM> may additionally interfere with an interference surface <NUM> of the adapter board <NUM>. The outer edge <NUM> of the anti-rotation plate <NUM> may form any suitable shape. As shown in <FIG>, the outer edge <NUM> may form a rectangular shape. This interference constrains the anti-rotation plates <NUM> against rotation with respect to the adapter board <NUM>. Some slight amount of rotation may still be possible depending on the tolerances of the various components. For example, the anti-rotation plate <NUM> may be constrained against rotating more than three degrees with respect to the adapter board <NUM>. Similarly, some slight relative rotation may be possible between the shank <NUM> of the bit <NUM> and the anti-rotation plate <NUM>. The bit <NUM> may be constrained against rotating more than three degrees with respect to the anti-rotation plate <NUM>.

The embodiment illustrated in <FIG> includes a linchpin <NUM> configured to prevent the bit <NUM> from backing out of the bit hole <NUM> in the adapter board <NUM>. The shank <NUM> of the bit <NUM> includes a hole <NUM> configured to receive the linchpin <NUM>. The hole <NUM> may be formed in the locking portion <NUM> of the shank <NUM>, for example. In the assembled state as shown in <FIG>, linchpins <NUM> are received within the holes <NUM> in the shanks <NUM>. The linchpin <NUM> may include a rotatably connected ring <NUM>, which may be rotated to the position shown in <FIG> to secure the linchpin <NUM> from backing out. Because the parallel engagement surfaces <NUM> are not perpendicular to the forward direction <NUM>, this configuration facilitates easy insertion of each linchpin <NUM> into a respective hole <NUM> in one of the shanks <NUM> without contacting the interference surface <NUM>. Similarly, this configuration also allows for removal of the linchpin <NUM> without interference from an adjacent linchpin <NUM> or bit <NUM>. The hole <NUM> and linchpin <NUM> may be oriented in any suitable direction, however.

In the embodiment illustrated in <FIG>, the engagement surfaces <NUM> are disposed perpendicular to the forward direction <NUM> when the system <NUM> is assembled. A respective hole <NUM> is formed in the interference surface <NUM> of the adapter board <NUM> for each linchpin <NUM>. Each hole <NUM> is configured to receive at least a portion of a respective linchpin <NUM>. Once the linchpins <NUM> are installed, the rings <NUM> of the linchpins <NUM> are rotated to the position shown in <FIG> to prevent the linchpins <NUM> from backing out of the holes <NUM> in the shanks <NUM>. In an alternative embodiment, the system <NUM> may secure the bits <NUM> against rotation without using any anti-rotation plates <NUM> whatsoever. Rather, each linchpin <NUM> may secure a respective bit <NUM> against rotation by engaging a respective hole <NUM> in the interference surface <NUM> and a respective hole <NUM> in the bit <NUM>.

The embodiment illustrated in <FIG> may alternatively be configured without holes <NUM> in the interference surface <NUM> to receive the linchpins <NUM>. Rather, the linchpins <NUM> may be oriented such that they do not contact the interference surface <NUM> as in the embodiment illustrated in <FIG>, for example. Any suitable orientation may be used, however. Alternatively, the linchpins <NUM> may be shorter in length, such that they do not contact the interference surface <NUM> when oriented as shown in <FIG>. Alternatively, the bit holes <NUM> in the adapter board <NUM> may be disposed farther from the interference surface <NUM> of the adapter board <NUM> than as illustrated in <FIG>.

Referring again to the embodiment illustrated in <FIG>, contact with more than one bit <NUM> adequately constrains the anti-rotation plate <NUM> against rotation. The anti-rotation plate <NUM>, however, may additionally be constrained against rotation in the same manner as described in the embodiment illustrated in <FIG>. In other words, the anti-rotation plate <NUM> may also contact one or more of the interference surface <NUM> of the adapter board <NUM> and an adjacent anti-rotation plate <NUM> as described with reference to <FIG>. This additional constraint, however, is not necessary for the embodiment shown in <FIG>. Rather, in this embodiment, the anti-rotation plate <NUM> may be shaped such that it does not contact or interfere with an adjacent anti-rotation plate <NUM> or the interference surface <NUM> of the adapter board <NUM>.

In another embodiment, the system <NUM> may be configured to only allow installation of the bits <NUM> in a forward-facing orientation. This configuration is not shown in the figures. For example, a portion of the outer edge <NUM> of the anti-rotation plate <NUM> that is opposite the interference surface <NUM> may include a protrusion, such as a tab. The protrusion and interference surface <NUM> may prevent the anti-rotation plates <NUM> from being installed such that the bit <NUM> faces backwards once installed. Alternatively, the outer edges <NUM> of the anti-rotation plates <NUM> may be configured to interlock with the outer edges <NUM> of adjacent anti-rotation plates <NUM> such that the anti-rotation plates <NUM> must be installed facing the same direction. The anti-rotation plate <NUM> and bit <NUM> may be similarly configured to prevent assembly with the bit facing any direction except forward. For example, the pair of engagement surfaces <NUM> of the locking portion <NUM> may be disposed in a non-parallel configuration. The slot <NUM> of the anti-rotation plate <NUM> may have a corresponding shape. Thus, the system <NUM> may be configured to prevent assembly with the bits <NUM> facing any direction except the forward direction <NUM>.

The forward direction <NUM> refers to the movement of the motor grader when driven forward. In the embodiments illustrated in <FIG> and <FIG>, the anti-rotation plates <NUM> are configured to secure the bits <NUM> facing the forward direction <NUM>. The adapter board <NUM> is secured to the motor grader such that the forward direction <NUM> of the motor grader is perpendicular to the interference surface <NUM> of the adapter board <NUM>. In other words, a <NUM> degree angle is formed between the forward direction <NUM> and the interference surface <NUM>. Alternatively, in another embodiment, the adapter board <NUM> may be secured at an angle such that the interference surface <NUM> is not perpendicular to the motor grader's movement in the forward direction <NUM>. For example, the adapter board <NUM> may be angled to one side such that the interference surface <NUM> and the forward direction <NUM> form an <NUM> degree angle, instead of a <NUM> degree angle. The anti-rotation plates <NUM> may be configured to secure the bits <NUM> at an angle offsetting the angle between the adapter board <NUM> and the forward direction <NUM>. Thus, the anti-rotation plates <NUM> may be configured to still secure the bits <NUM> facing the forward direction <NUM> of the motor grader. In one embodiment, the system <NUM> may include several sets of anti-rotation plates <NUM>. A first set may be configured to secure the bits <NUM> at an <NUM> degree angle with respect to the interference surface <NUM>, for example. A second set may be configured to secure the bits <NUM> at a <NUM> degree angle with respect to the interference surface <NUM>, for example, and so forth. Thus, each set of anti-rotation plates <NUM> may secure the bits <NUM> at an angle corresponding to the angle of the adapter board <NUM> with respect to the forward direction <NUM>. Thus, the adapter board <NUM> may be secured to the motor grader with the interference surface <NUM> at a variety of angles with respect to the forward direction <NUM>, for example, between <NUM> degrees and <NUM> degrees. An appropriate set of anti-rotation plates <NUM> may then be selected corresponding to the orientation of the adapter board <NUM> such that all of the bits <NUM> are still secured facing the forward direction <NUM> of the motor grader's movement.

The disclosed bit securing system <NUM> finds potential application in any device requiring a bit <NUM> to be secured in a particular orientation. The disclosed bit securing system <NUM> finds particular applicability with motor graders having adapter boards <NUM> securing bits <NUM>. Assembly of the bit securing system <NUM> will now be explained.

One embodiment of the system <NUM> is shown in <FIG>. To assemble the system <NUM>, each shank <NUM> of a respective bit <NUM> is inserted within a respective bit hole <NUM> of the adapter board <NUM>. Once the shank <NUM> is fully inserted, the shoulder <NUM> of the bit <NUM> contacts the lower surface <NUM> of the adapter board <NUM>. Then, the anti-rotation plate <NUM> is positioned on the upper surface <NUM> of the adapter board <NUM> such that the shanks <NUM> of at least two bits <NUM> are received within the slots <NUM> of the anti-rotation plate <NUM> and such that the anti-rotation plate <NUM> engages the locking portions <NUM> of the bits <NUM>. Linchpins <NUM> are then installed in the holes <NUM> in the shanks <NUM> to prevent the bits <NUM> from backing out of the adapter board <NUM>. The rings <NUM> of the linchpins <NUM> are rotated to the position shown in <FIG> to prevent the linchpins <NUM> from backing out of the holes <NUM> in the shanks <NUM>.

The disclosed system <NUM> easily facilitates replacing worn bits <NUM>. As they become worn, the bits <NUM> can be individually replaced, if necessary, by reversing the assembly process described above. Unlike snap rings, the linchpins <NUM> used in the disclosed embodiments can be easily removed by hand without specialized tools.

The disclosed system <NUM> also constrains the bits <NUM> against rotation after the lower surface <NUM> of the adapter board <NUM> has become severely worn. As the adapter board <NUM> and bits <NUM> are forced against the ground, terrain inconsistencies such as rocks or gravel, may scrape and grind against the lower surface <NUM> of the adapter board <NUM>. As the lower surface <NUM> of the adapter board <NUM> is worn down by these abrasions, the anti-rotation plate <NUM> and the locking portion <NUM> of the bit <NUM> remain unaffected because they are disposed on the upper surface <NUM> of the adapter board <NUM>. Additionally, as the adapter board <NUM> becomes severely worn, the abrasions may reduce the thickness of the adapter board <NUM> as measured between the lower surface <NUM> and the upper surface <NUM>. Despite the reduced thickness of the adapter board <NUM>, however, the anti-rotation plates <NUM> may constrain the bits <NUM> against rotation by engaging the locking portions <NUM> of the bits <NUM>. As explained in the previous section, the locking portions <NUM> may be partially received within the bit holes <NUM> below the upper surface <NUM> of the adapter board <NUM>. Thus, once the thickness of the adapter board <NUM> is reduced, a segment of the locking portions <NUM> which was previously received within the bit holes <NUM> may now extend above the upper surface <NUM> such that the anti-rotation plate <NUM> may still engage the locking portions <NUM> despite the reduced thickness of the adapter board <NUM>. This may extend the useful life of the bits <NUM>.

The disclosed system <NUM> may also provide increased versatility. As explained in the previous section, the adapter board <NUM> may be secured to the motor grader such that the interference surface <NUM> is not perpendicular to the forward direction <NUM> of the motor grader's movement. For example, the adapter board <NUM> may be secured at an angle such that dirt and rocks dislodged by the bits <NUM> are pushed to one side of the adapter board <NUM>, similar to the operation of a snow plow. A set of appropriately configured anti-rotation plates <NUM> may be selected depending on the desired angle of the adapter board <NUM> such that the bits <NUM> are still secured facing the forward direction <NUM>. Because the bit holes <NUM> in the adapter board <NUM> are circular, the anti-rotation plates <NUM> may be configured to secure the bits <NUM> at any suitable angle with respect to the adapter board <NUM>.

Lastly, the disclosed system <NUM> may be manufactured using simple and inexpensive processes. For example, a simple drilling process may be used to form the circular bit holes <NUM> in the adapter board <NUM>. The disclosed system <NUM> does not require any non-circular slot <NUM> in the adapter board <NUM> to secure the bits <NUM>. The locking portions <NUM> of the bits <NUM> may also be easily formed by removing material from an initially cylindrical shank <NUM> using any suitable technique, such as machining, cutting, grinding etc. The anti-rotation plate <NUM> may also be easily formed using any suitable technique including forming a flat plate and then punching or cutting the slot <NUM>. Alternatively, the anti-rotation plate <NUM> may be cast in a mold.

Claim 1:
A bit (<NUM>) securing system (<NUM>) comprising:
at least two bits (<NUM>), each bit including a respective shank (<NUM>), each shank (<NUM>) including a respective locking portion (<NUM>);
an adapter board (<NUM>) including at least two holes (<NUM>), each respective hole of the adapter board (<NUM>) configured to receive one respective shank (<NUM>) of the at least two bits (<NUM>); and
an anti-rotation plate (<NUM>) configured to engage the respective locking portions (<NUM>) of the shanks (<NUM>) of the at least two bits (<NUM>) such that the anti-rotation plate (<NUM>) constrains the at least two bits (<NUM>) against rotation with respect to the adapter board (<NUM>);
characterised in that the adapter board (<NUM>) includes a lower surface (<NUM>) and an upper surface (<NUM>);
each bit (<NUM>) includes a respective shoulder (<NUM>);
each shank (<NUM>) extends from a respective shoulder (<NUM>); and
when each shank (<NUM>) of the at least two bits (<NUM>) are received within a respective hole of the adapter board (<NUM>) with each shoulder (<NUM>) abutting the lower surface (<NUM>) of the adapter board (<NUM>), the respective locking portions (<NUM>) extend outside each respective hole from the upper surface (<NUM>) of the adapter board (<NUM>).