Road structure – process – or apparatus – Apparatus – Tamper
Reexamination Certificate
2000-11-09
2003-04-22
Shackelford, Heather (Department: 3673)
Road structure, process, or apparatus
Apparatus
Tamper
C404S133050
Reexamination Certificate
active
06551022
ABSTRACT:
BACKGROUND TO THE INVENTION
The invention relates to a compactor machine and in particular to one of the kind operated by a pedestrian for fairly light compacting of the ground.
Compactor machines of this kind are generally known as forward vibrating plate compactors, and many slightly different forms are known. In general they comprise an engine which transmits power via a pulley belt to an eccentric mass unit attached to a base plate. The mass is rotated generating a centrifugal force, and simultaneously applying a downward force with motion in a forward direction. The machine is guided by a pedestrian operator via a steering handle.
A major problem with many of the prior art compactors of this type is the level of vibration transmitted to the hands of the operator, and generally known as Hand-Arm Vibration (H.A.V.). Various approaches to the problem have been tried without much success, as significant vibration is still transmitted. This can lead to a medical condition, commonly known as Vibration White Finger, in operators who use these machines for extended periods of time, and which is clearly undesirable. The European Union has issued guidelines for safe levels of H.A.V., which can be experienced over an eight hour duration, of 2.5 ms
−2
. If manufacturers produce machines with levels of H.A.V. higher than this level they are required to state this in their product literature.
Clearly, if the level of H.A.V. can be reduced the operators' health and comfort are considerably enhanced, and longer working periods can also be contemplated.
It is an object of the present invention to mitigate the above described problem.
SUMMARY OF THE INVENTION
According to the present invention there is provided compactor machine of the kind controlled by a pedestrian operator and including a base plate, an operative unit, mounted on the base plate, and having a support plate and a main frame, and means to cause the base plate to vibrate when in use, and a handle by which the operator controls the machine in use, wherein the compactor machine further comprises a secondary frame mounted on the main frame by means of a plurality of first damping mounts and wherein the handle is mounted on the secondary frame.
Preferably the secondary frame is mounted on the main frame distant from the base plate.
The handle may be pivotally mounted on the secondary frame.
Preferably the plurality of first damping mounts comprises four arranged substantially in a rectangle in a plane substantially parallel to the base plate. Each first damping mount may be inclined upwardly and outwardly.
The main frame may substantially define the outer dimensions of the operative unit.
The plurality of first damping mounts may have a stiffness in the range 10 to 20 Nmm
−1
, or it may be in the range 12.5 to 17.5 Nmm
−1
.
Preferably the operative unit is mounted on the base plate by means of a plurality of second damping mounts.
The plurality of second damping mounts generally comprises four arranged substantially in a rectangle.
Conveniently the plurality of second damping mounts have a stiffness in the range 30 to 70 Nmm
−1
, or it may be in the range 40 to 60 Nmm
−1
.
REFERENCES:
patent: 3782845 (1974-01-01), Briggs et al.
patent: 4043694 (1977-08-01), Mullen
patent: 4067244 (1978-01-01), Baumers
patent: 5645370 (1997-07-01), Zürbes et al.
patent: 5934825 (1999-08-01), Waldenberger
patent: 1396373 (1975-06-01), None
patent: 2016563 (1979-09-01), None
patent: 1578696 (1980-11-01), None
patent: 2115466 (1983-09-01), None
patent: 2315796 (1998-02-01), None
Benford Limited
MacMillan Sobanski & Todd LLC
Shackelford Heather
Singh Sunil
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