Endless belt power transmission systems or components – Plural belts or plural output loads – Plural belts having interengaged drive surfaces
Reexamination Certificate
1997-11-17
2001-11-27
Bucci, David A. (Department: 3682)
Endless belt power transmission systems or components
Plural belts or plural output loads
Plural belts having interengaged drive surfaces
C474S111000, C474S140000, C198S833000
Reexamination Certificate
active
06322467
ABSTRACT:
BACKGROUND OF THE INVENTION
Drive chains are used to transfer power from a source of rotational energy to a secondary chain or similar device such as the power chain in a power and free conveyor system. The drive chain is connected between two sprockets, at least one of which is powered by a drive shaft, and includes a plurality of teeth or dogs extending outwardly from the chain for engaging the driven chain. The drive chain is positioned in proximity to the driven chain, and a backup bar is used to guide the drive chain and hold it against the driven chain. This allows the teeth on the drive chain to engage the secondary chain and transmit the rotation of the drive chain to the driven chain.
A backup bar must be carefully positioned in order to transfer power from the drive chain to the driven chain in an efficient manner. If the bar does not hold the drive chain sufficiently firmly against the conveyor chain, the teeth may slip, resulting in a lower or inconsistent level of power. If the drive chain is pressed too firmly against the conveyor chain, it may interfere with the smooth rotation of the drive shaft. If the drive chain is not properly aligned with the chain being driven, damage may result to one or both of the chains, shortening the lives thereof. Furthermore, significant stresses are placed on the backup bar by the drive chain during operation which could alter the orientation of the backup bar if it were not securely fastened in place. Therefore, drive chain assemblies are constructed with backup bars bolted in place to hold the drive chain precisely in position.
It occasionally becomes necessary to disengage the drive chain from the conveyor chain such as when performing certain maintenance tasks or when auxiliary drives are connected to the conveyor. In order to do this, it is necessary to unbolt the backup bar and remove it, or reposition it so that it no longer holds the drive chain against the conveyor chain and refasten the backup bar in this new position. Because the unbolting of the backup bar can introduce slack into the drive chain, the person performing this operation must be careful to ensure that the drive chain is completely clear of the conveyor chain and not drooping onto the conveyor or onto any other moving parts. It may also be necessary to secure the drive chain to keep it clear of the conveyor chain. Care must be taken not to operate the drive chain when slack is present because this could cause the drive chain to slip off of the drive sprockets and cause damage to nearby equipment such as the drive shaft. This repositioning process requires a variety of tools and special skills and can take approximately 15 minutes, even when performed by a skilled technician or engineer. It would therefore be desirable to provide a backup bar assembly that could be repositioned quickly to positively engage or disengage a drive chain from a conveyor chain and which could be operated without special tools or skills, yet which was still capable of securely holding a backup bar in a required position.
SUMMARY OF THE INVENTION
These and other objects are accomplished by the present invention which comprises a backup bar assembly for use in connection with a drive chain which assembly can be repositioned with an actuator operable either automatically or by hand. The actuator is preferably lockable in only one of two positions to ensure that the backup bar is either positively holding the drive chain against the conveyor chain or is separated from the drive chain, and that it is not in some intermediate position. Furthermore, the backup bar assembly may include a structure for placing tension on the drive chain to hold it away from the driven chain even when the drive chain is disengaged from the driven chain.
In a preferred embodiment of the subject invention, the drive chain assembly comprises first and second sprockets, each supported by a rotatable shaft for rotation about the longitudinal axis of the shaft. At least one of the shafts is a drive shaft connected to a power source. An endless drive chain is connected between the sprockets and rotates about the sprockets when the drive shaft turns. A backup bar is attached to a backup bar support and the backup bar support is connected to an actuator which in turn is connected to a structure that is fixed with respect to the sprockets. The backup bar is positioned inside the curve defined by the endless drive chain and in alignment with the drive chain. The actuator can be manipulated by hand to move the backup bar against the drive chain to push the drive chain into engagement with the chain being driven and then locked in place to hold the drive chain against the driven chain. The actuator can also be locked in a second position to hold the backup bar away from the drive chain.
Preferably, when the actuator is in this second position, the backup bar support places tension on the drive chain to hold it away from the chain being driven. The drive chain may still be turning when it is disengaged from the driven chain. Therefore, it is important that it be held away from the driven chain so that the driven chain will not change position when it is supposed to be at rest. Likewise, the driven chain may continue to be driven by an auxiliary drive after the main drive chain is disengaged. It is therefore important that the drive chain be held clear of the driven chain to prevent it from interfering with the free movement thereof.
It is therefore the principal object of the present invention to provide an apparatus for moving a drive chain into and out of engagement with another object.
It is another object of the present invention to provide an apparatus of the forgoing character which can be operated without the use of tools.
It is a further object of the present invention to provide an apparatus of the forgoing character which can be operated by a person without any special skills.
It is yet another object of the present invention to provide an apparatus for reducing slack in a drive chain when it is disengaged from a driven chain.
It is still another object of the present invention to provide an apparatus of the forgoing character that is lockable in a first or second position to positively hold a drive chain against or away from a driven chain.
It is yet another object of the present invention to provide an actuator for a backup bar.
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Carr Lane Manufacturing Co., catalog, p. 40TC, Feb. 1998.
Bailey Ronald L.
Hook Christopher A.
Bucci David A.
Dickinson Wright PLLC
Jervis B. Webb Company
Joyce William C
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