U.S. patent number 3,686,993 [Application Number 05/105,427] was granted by the patent office on 1972-08-29 for shoulder strap-operated pitch-changing means for spanish guitars.
This patent grant is currently assigned to Columbia Broadcasting System, Inc.. Invention is credited to Clarence L. Fender.
United States Patent |
3,686,993 |
Fender |
August 29, 1972 |
SHOULDER STRAP-OPERATED PITCH-CHANGING MEANS FOR SPANISH
GUITARS
Abstract
The pitch-changer is mounted in a cavity in the body of a
Spanish guitar, and incorporates a second-class lever in the form
of a bolt which is adjustably associated with a link, the latter
being connected to the string to be tensioned in order to change
the pitch thereof. The bolt is pivoted by a bell-crank lever which,
in turn, is connected to the shoulder strap for operation thereby.
The link is adjustable along the length of the bolt to thus change
the degree of pulling of the string in response to a predetermined
movement of the bell crank and the bolt. Stop means are provided to
limit movement of the bell crank to a predetermined angle, and a
torsion spring is provided to counterbalance the weight of the
guitar body, the mounting of the torsion spring being such that
there is no lateral force against the pivot for the bell crank.
Inventors: |
Fender; Clarence L. (Fullerton,
CA) |
Assignee: |
Columbia Broadcasting System,
Inc. (New York, NY)
|
Family
ID: |
22305789 |
Appl.
No.: |
05/105,427 |
Filed: |
January 11, 1971 |
Current U.S.
Class: |
84/312R; 84/313;
257/720; 257/750; 984/120 |
Current CPC
Class: |
G10D
3/147 (20200201) |
Current International
Class: |
G10D
3/00 (20060101); G10D 3/14 (20060101); G10d
003/14 () |
Field of
Search: |
;84/312,313 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Wilkinson; Richard B.
Assistant Examiner: Franklin; Lawrence R.
Claims
I claim:
1. A Spanish guitar incorporating pitch-changing means operated by
the shoulder strap, which guitar comprises:
a guitar body having a neck extended therefrom,
a plurality of guitar strings mounted in tensioned relationship
over said neck and over said body,
a lever pivotally mounted on said body,
stop means to limit the pivotal movement of said lever in such
manner that said lever may only pivot between first and second
predetermined positions angularly offset from each other,
means to connect said lever to at least one of said strings to
effect changing of the tension of said one string in response to
pivoting of said lever between said predetermined positions,
said means to connect said lever to said one string comprising a
second-class lever pivotally connected to said body and operated by
said first-mentioned lever,
said means to connect said first-mentioned lever to said one string
further comprising a first-class lever connected to said one
string,
said means to connect said first-mentioned lever to said one string
further comprising a turnbuckle to connect said first-class lever
to said second-class lever,
means to adjust said connector means to achieve a predetermined
changing of the pitch of said one string in response to said
pivoting of said first-mentioned lever between said predetermined
positions,
said means to adjust said connector means comprising means to shift
along said second-class lever the connection thereof to said
turnbuckle,
a shoulder strap connected at one end to said first-mentioned lever
and at the other end to said guitar body, and
spring means to bias said first-mentioned lever to said first
predetermined position,
said spring means being sufficiently strong to prevent the weight
of the guitar from shifting said first-mentioned lever away from
said first predetermined position whereby the guitarist must
intentionally operate said shoulder strap to shift said
first-mentioned lever to said second predetermined position and
thus achieve said predetermined changing of the pitch of said one
string.
2. The invention as claimed in claim 1, in which said second-class
lever is an elongated bolt adapted to be rotated about the
longitudinal axis thereof, and in which said means to adjust said
connection includes a combination nut and pivot element threadedly
associated with said bolt for shifting therealong in response to
rotation of said bolt about the longitudinal axis thereof.
3. A Spanish guitar incorporating pitch-changing means operated by
the shoulder strap, which guitar comprises:
a guitar body having a neck extended therefrom,
a plurality of guitar strings mounted in tensioned relationship
over said neck and over said body,
an elongated second-class lever disposed transversely of said
strings,
one end of said second-class lever being pivotally connected to
said body,
said second-class lever being an elongated bolt,
a shoulder strap having one end thereof connected to said body,
means to connect the other end of said shoulder strap to the other
end of said second-class lever and in such manner that pulling on
said shoulder strap effects pivotal movement of said second-class
lever generally in a plane parallel to said body, and
means to connect an intermediate portion of said second-class lever
to at least one of said strings to thus effect changing of the
tension in said one string in response to said pivotal movement of
said second-class lever,
said means to connect said second-class lever to said one string
including a combination pivot and nut element threadedly associated
with said bolt for shifting therealong in response to rotation of
said bolt about the longitudinal axis thereof,
said means to connect said second-class lever to said one string
further including a first-class lever directly connected to said
string, and a link to connect said first-class lever to said
combination pivot and nut element.
4. The invention as claimed in claim 3, in which said combination
pivot and nut element is a loop of wire looped around said bolt,
and in which said link includes a turnbuckle adapted to maintain
sufficient tension on said loop of wire to keep the same threadedly
associated with said bolt.
5. The invention as claimed in claim 3, in which the pivot
connection between said one end of said second-class lever and said
body comprises a pivot element mounted on the back of said guitar
body and having an opening therethrough to receive said bolt, said
bolt having a head disposed on the side of said pivot element
remote from said other end of said second-class lever, said head
being adapted to be rotated by the guitarist to thereby shift said
combination pivot and nut element along said bolt.
6. A Spanish guitar incorporating pitch-changing means operated by
the shoulder strap, which guitar comprises:
a guitar body having a neck extended therefrom,
a plurality of guitar strings mounted in tensioned relationship
over said neck and over said body,
said guitar strings being generally parallel to each other,
an elongated externally-threaded element, fulcrum means provided
adjacent one end of said externally-threaded element to pivotally
mount said externally-threaded element to said body,
a shoulder strap having one end connected to said body, means to
connect the other end of said strap to the end of said
externally-threaded element remote from said one end thereof,
whereby pulling on said strap by the guitarist effects pivotal
movement of said externally-threaded element about said fulcrum
means,
combination nut and pivot means provided on said
externally-threaded element between said one end thereof and said
remote end thereof,
said combination nut and pivot means being a loop of wire
threadedly associated with said externally-threaded element and
adapted to pivot relative thereto,
means to rotate said externally-threaded element about the
longitudinal axis thereof to thereby shift said combination nut and
pivot means along said externally-threaded element, and
means to connect said combination nut and pivot means to at least
one of said strings.
7. The invention as claimed in claim 6, in which said means to
connect said combination nut and pivot means to said one string
includes turnbuckle means to maintain tension on said loop of wire
and thus maintain said loop threadedly associated with said
externally-threaded element, and further includes lever means
connected to said string.
8. The invention as claimed in claim 6, in which said means to
rotate said externally-threaded element comprises head means at
said one end of said externally-threaded element and adapted to
rotate the same about the longitudinal axis thereof.
9. The invention as claimed in claim 6, in which said fulcrum means
comprises a fulcrum element fixedly associated with said guitar
body, said fulcrum element having an opening therethrough to
receive said one end of said externally-threaded element.
10. The invention as claimed in claim 9, in which said
externally-threaded element is mounted in a recess in the back of
said guitar body, and in which said fulcrum means is provided on
the cover plate for said recess, said cover plate being adapted to
prevent ingress of dirt into said recess, said externally-threaded
element having a head mounted externally of said cover plate for
operation by the guitarist to thereby rotate said
externally-threaded element and shift said combination nut and
pivot means therealong without removing said cover plate.
11. A guitar incorporating shoulder strap-operated pitch-changing
means, which comprises:
a guitar body having a neck extended therefrom,
a plurality of strings mounted over said neck and said body in
tensioned condition,
a pivot element fixedly mounted on said body,
a lever pivotally connected to said pivot element,
a shoulder strap having one end thereof connected to one part of
said lever,
the other end of said strap being connected to said body,
means to connect another part of said lever to at least one of said
strings,
whereby to change the tension of said one string in response to
pivoting of said lever by said strap, and
a torsion spring mounted around said pivot element,
one end of said spring being engaged with said lever to bias the
same to a predetermined position,
the other end of said spring being fixed in position relative to
said body,
said spring being sufficiently strong that the weight of the guitar
will not shift said lever away from said predetermined
position.
12. The invention as claimed in claim 11, in which said means to
connect said lever to said one string includes a second lever
operated by said first-mentioned lever, a link connected to said
second lever, and a third lever connected to said link and also to
said one string, said second and third levers being pivotally
associated with said guitar body.
13. The invention as claimed in claim 11, in which stop means are
provided to limit the pivotal movement of said lever, said stop
means permitting said lever to pivot between said predetermined
position and another predetermined position angularly offset
therefrom.
14. A Spanish guitar having pitch-changing means operated by the
shoulder strap, which guitar comprises:
a solid body having a generally planar face and a generally planar
back disposed in spaced and generally parallel relationship to each
other,
a neck extended from one end of said body and generally parallel to
the planes of said face and said back, a bridge mounted on said
face of said body, a plurality of generally parallel strings
mounted in tensioned relationship over said neck, over said face,
and over said bridge, a recess provided in said back of said body,
an elongated second-class lever mounted in said recess at a region
between said bridge and said neck,
said second-class lever being disposed generally parallel to the
planes of said face and said back and also being disposed
transverse to said strings,
means to pivotally connect one end of said second-class lever to
said body to permit pivotal movement of said lever in a plane
generally parallel to the planes of said face and said back,
said one end of said second-class lever being relatively adjacent
the edge of said body that is held lowermost by the guitarist when
the guitar is in playing position,
a fixed pivot axis provided relatively adjacent the edge of said
body that is held uppermost by the guitarist when the guitar is in
playing position, a bell crank pivotally connected to said fixed
pivot axis, one arm of said bell crank lever being generally
aligned with said second-class lever and being connected thereto, a
shoulder strap connected at one end thereof to the other end of
said bell crank,
the other end of said shoulder strap being connected to said
body,
spring means to bias said bell crank to a predetermined pivoted
position at which said other end of said bell crank is shifted
toward said lowermost edge of said body,
said spring means being sufficiently strong to prevent the weight
of the guitar from effecting pivoting of said bell crank to shift
said other end toward said upper-most edge of said body,
a lever extended through said body from said recess to the vicinity
of said bridge,
said last-mentioned lever being connected to at least one of said
strings, and
a link disposed in said recess and connected between said
last-mentioned lever and an intermediate region of said
second-class lever between said one end thereof and said other end
thereof.
15. The invention as claimed in claim 14, in which said
second-class lever is an elongated threaded element, in which said
means to pivotally connect said one end of said second-class lever
to said body is adapted to permit rotation of said threaded element
about the longitudinal axis thereof, in which means are provided to
permit the guitarist to rotate said threaded element about said
longitudinal axis thereof, and in which said link is connected to
said second-class lever by a combination threaded element and pivot
means whereby said connection between said link and said threaded
element shifts along said threaded element in response to rotation
thereof, and whereby said threaded element may pivot relative to
said link upon shifting of said second-class lever by said bell
crank.
16. The invention as claimed in claim 14, in which a cover plate is
mounted over said recess, in which said means to pivotally connect
said one end of said second-class lever to said body comprises a
recessed portion of said cover plate, and in which said
second-class lever is a bolt which extends through an oversize
opening in said recessed portion of said cover plate, said bolt
having a head disposed exteriorly of said cover plate for access by
the guitarist.
17. The invention as claimed in claim 14, in which said means to
connect said one end of said bell crank to the other end of said
second-class lever comprises a flange on said bell crank and having
an opening therein through which said second-class lever extends,
said second-class lever being externally threaded, and in which a
nut is provided on said second-class lever adjacent said
flange.
18. The invention as claimed in claim 14, in which said link
includes a turnbuckle, in which said second-class lever is an
externally threaded element, and in which said link further
includes a loop of wire extended from said turnbuckle around said
externally threaded element and forming a combination nut and pivot
means permitting shifting of said wire along said second-class
lever in response to rotation of said lever about the longitudinal
axis thereof.
19. The invention as claimed in claim 14, in which an additional
link is provided and is connected to a lever connected with another
of said strings, in which an additional second-class lever is
provided and connected to said bell crank, and in which said
additional link is pivotally associated with said additional
second-class lever.
20. The invention as claimed in claim 14, in which a cover is
provided for said recess, said cover having a slot therein, in
which said bell crank has an exterior portion disposed beneath said
cover and connected to said shoulder strap, said exterior portion
of said bell crank being pivotally connected to said fixed pivot
axis, in which said bell crank has an interior angular portion
disposed in said recess and above said cover, and in which an
element is extended between said exterior and interior portions of
said bell crank and through said slot, said last-named element
cooperating with the ends of said slot to limit the pivotal
movement of said bell crank, said bell crank being in said
predetermined position when said element is at one end of said slot
and being in an other predetermined position when said bell crank
is at the other end of said slot.
21. The invention as claimed in claim 20, in which said fixed pivot
axis is a bolt extended through said exterior portion of said bell
crank, through said cover plate and through said interior portion
of said bell crank, and in which an enlarged nut is provided in
said recess around said bolt and on the opposite side of said
interior portion from said cover plate.
22. The invention as claimed in claim 21, in which a helical
torsion spring is provided around said enlarged nut, in which said
element which extends through said slot is a second bolt, in which
a second enlarged nut is threadedly associated with said second
bolt on the side of said interior portion remote from said cover
plate, in which said torsion spring has an arm which extends into
bearing engagement with said second nut, in which a third nut is
mounted on said cover plate and in said recess, and in which a
second arm of said torsion spring engages said third nut.
23. The invention as claimed in claim 14, in which said lever
extended through said body has a passage therethrough to receive
said one string, in which said bridge is adjustably mounted on a
plate disposed on the face of said body, said plate having an
opening therethrough to receive said lever and said string
therethrough, and in which said lever is adapted to pivot on one
edge of said opening.
24. A Spanish guitar incorporating pitch-changing means operated by
the shoulder strap, which guitar comprises:
a guitar body having a neck extended therefrom,
a plurality of guitar strings mounted in tensioned relationship
over said neck and over said body,
an elongated second-class lever disposed transversely of said
strings,
one end of said second-class lever being pivotally connected to
said body,
a shoulder strap having one end thereof connected to said body,
means to connect the other end of said shoulder strap to the other
end of said second-class lever and in such manner that pulling on
said shoulder strap effects pivotal movement of said second-class
lever generally in a plane parallel to said body,
said means to connect said other end of said shoulder strap to said
other end of said second-class lever comprising a bell crank lever
pivotally connected to said body,
one arm of said bell crank lever being generally aligned with said
second-class lever and being connected thereto, and
means to connect an intermediate portion of said second-class lever
to at least one of said strings to thus effect changing of the
tension in said one string in response to said pivotal movement of
said second-class lever.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the field of Spanish guitars which are
provided with shoulder strap-operated mechanisms adapted, at will
of the guitarist, to change the pitch of one or more strings by a
predetermined increment.
2. Description of Prior Art
Shoulder strap-operated string pitch changers were, to the best
knowledge of applicant, introduced by the invention of U.S. Pat.
No. 3,512,443, issued May 19, 1970. The guitar described in such
patent is fully operative to perform the new function described and
claimed in such patent. However, the mechanism of such patent is
not commercially practical for mass manufacture. As shown in FIG. 4
of such patent, the guitar body is rendered extremely bulky by the
presence of a cover which covers substantially the entire back of
the guitar. Furthermore, the spring means is a long tension spring
which not only requires much room, but also places a strain upon
the bearing for the bell-crank lever.
Very importantly, the mechanism of the U.S. Pat. No. 3,512,443 does
not incorporate an adjustment means whereby a fixed amount of
pivoting of the bell crank, as limited by stop means, will produce
a predetermined desired change (for example, one-half tone) in the
pitch of the string. Due to different characteristics of strings
which generate different pitches in a guitar, and also due to the
characteristics of strings which are adapted to produce the same
pitch (but which vary for production reasons), a certain amount of
pivoting of the bell crank will not normally produce the same pitch
change for one string as for another. Therefore, unless the
guitarist is to be forced to attempt to sense by ear when the
desired pitch change has been achieved, as distinguished from
pivoting the bell crank through a predetermined distance until a
stop means is engaged, it is necessary and important that the
guitarist be permitted to tune each string both for the
lowest-pitch and the highest pitch tone (the latter being normally
a one-half tone above the former). The present invention achieves
this result in a simple and economical manner, and which permits
tuning to be effected from outside the guitar body wherein the
mechanism is mounted.
The present invention converts the operative but commercially
impractical mechanism of said u.S. Pat. 3,512,443 into a
commercially practical, mass producible mechanism having greatly
enhanced characteristics relative to ease of playing, tunability,
adjustability, wear, and other factors. This is accomplished by the
lever, link, connector and other members described below and
recited in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a bottom plan view of a Spanish guitar incorporating the
shoulder strap-operated pitch-changing means of the present
invention;
FIG. 2 is an interior plan view of the mechanism, looking outwardly
from the interior of the guitar body, the mechanism being shown in
its position prior to pulling on the shoulder strap by the
guitarist;
FIG. 3 is a view generally corresponding to portions of FIG. 2, but
showing the mechanism in its actuated position after the bell crank
has been pulled to its extreme position by the guitarist;
FIG. 4 is an enlarged sectional view taken along line 4--4 of FIG.
2;
FIG. 5 is an enlarged longitudinal sectional view taken on line
5--5 of FIG. 2;
FIG. 6 is a fragmentary sectional view along line 6--6 of FIG.
2;
FIG. 7 is an isometric view of the mechanism, but with the guitar
body unshown, and illustrating only a portion of the shoulder
strap;
FIG. 8 is a view corresponding generally to portions of FIG. 2, but
showing a modified construction wherein two strings of the guitar
may be stretched, instead of one string thereof; and
FIG. 9 is a fragmentary sectional view on line 9--9 of FIG. 8.
DESCRIPTION OF PREFERRED EMBODIMENTS:
Referring particularly to FIG. 1, the mechanism of the invention is
incorporated in the back portion of the body 10 of a Spanish
guitar, said guitar having a neck 11 at the outer end of which is
provided a head 12. The body 10, is, in the present illustration, a
solid wooden body (or plastic) body although the invention may also
be provided in hollow-body guitars.
Body 10 has a face and a back which lie in generally parallel
planes (to which neck 11 is also generally parallel), it being
understood that the appended claims also apply to guitars wherein
the generally parallel face and back are contoured. A plurality of
generally parallel guitar strings, normally six, are disposed over
neck 11 and over the face of body 10 as shown in my prior U.S. Pat.
no. 3,290,981, issued Dec. 13, 1966. The tension in such strings is
regulated by tuning pegs or screws (also shown in such prior
patent) on head 12.
It is a feature of the present invention that the great majority of
the components of the pitch-changing device are recessed into the
back of body 10, and in a recess which is sufficiently small that
the body is not weakened substantially but instead may readily
withstand the stresses imposed by the strings of the guitar. The
recess is numbered 13, and has an outline which is shown by phantom
lines 14 in FIG. 2. A major portion of the recess 13 is disposed
between the neck 11 and the bridge region (describes below) of the
guitar.
Provided over a generally L-shaped portion of the recess 13, such
portion being relatively adjacent the neck 11 of the guitar, is an
L-shaped cover and mounting plate 16. Such plate 16 is secured to
body 10 by means of screws which are represented at 17 (FIG. 6). An
operating arm 18 of a bell-crank lever, described below, is mounted
exteriorly of the plate 16. Operating arm 18, and the entire
bell-crank, are pivotally mounted to the plate 16 (and thus to body
10) by means of a bolt 19 which extends through the arm 18, through
the plate 16 and into a large-diameter nut 21 (FIG. 4).
The bolt 19 also extends through the corner or elbow portion of a
bell-crank lever 22, there being a plastic bushing or washer 23
(FIG. 4) between the lever 22 and the interior surface of plate
16.
The bell-crank lever 22 has an arm 24 which is disposed inwardly
adjacent and parallel to the plate 16, and also parallel to the
above-indicated operating arm 18. The remaining arm 25 of the
bell-crank lever 22 extends at a right angle to arm 24 for
operation of a second-class lever as stated below.
Operating arm 18 is fixedly connected to arm 24 of bell-crank lever
22 by means of a bolt 26 (FIG. 4). Such bolt extends inwardly
through a slot 27 in plate 16, and through arm 24 of the
bell-crank, for threaded connection to an oversize nut 28. The slot
27 has such a length that it permits a predetermined amount of
pivotal movement of the bell-crank lever 22 and its operating arm
18 about pivot bolt 19.
Bolt 19 is not threadedly related to plate 16, but is threaded
through arm 24 as well as through nut 21. Thus, nut 21 serves as a
lock nut. Similarly, bolt 26 is threaded through arm 24, so that
nut 28 serves as a lock nut.
It will be seen that the operating arm 18 moves parallel to and
conjointly with the arm 24 of the bell-crank 22. Therefore, these
two elements may for some purposes both be regarded as portions of
the bell-crank.
The arms 18 and 24 extend generally parallel to the neck 11 of the
instrument, being offset from such neck in a direction toward the
edge 29 (FIG. 1) of the guitar body 10. Such edge 29 is the one
held uppermost when the instrument is played by a musician. Arm 25
of the bell-crank extends in a direction away from such edge 29 and
toward the longitudinal axis of the neck 11. Thus, the arms 18 and
24 are generally parallel to but offset laterally from, the strings
of the instrument, whereas the arm 25 is transverse to such
strings.
The free end of operating arm 18 is provided with a button 31 for
connection to the end of the shoulder strap 32 of the guitar. The
remaining end of the strap is connected to a button 33 which is
fixed on the tail portion of body 10. Thus, as described in the
cited U.S. Pat. No. 3,512,443, pulling on the strap 32 by the neck
of the player (or pushing on the body 10 by the arms of the player)
causes pivotal movement of operating arm 18 and thus of bell-crank
22.
An elongated second-class lever 35 is disposed transversely of the
extended axis of neck 11, that is to say, transversely of the
guitar strings, and generally across such extended axis. Lever 35
is thus in general alignment with arm 25. Stated more definitely,
the lever 35 is an elongated bolt having a head region 37 (FIG. 6)
which is pivotally mounted in an oversize opening 38 formed in a
recessed portion 39 of the cover and mounting plate 16. Such
recessed portion 39 is disposed on the opposite side of the guitar
axis from the bell crank 22, and generally in line with the arm 25
of the bell crank. Thus, the head region 37 is relatively adjacent
the lowermost edge (FIG. 1 of the body 10. As best shown in FIG. 6,
the recessed portion 39 has an inclined wall 41 which extends
inwardly, and a much more sharply inclined wall 42 which is
provided with the opening 38 for the lever bolt.
The other end of bolt 35, remote from head 37 thereof, extends
through an oversize opening 43 (FIG. 6) in a flange 44 provided at
the free end of arm 25 of the bell-crank. A nut 46 is mounted on
such bolt end, and a helical compression spring 47 is seated
between the nut and the flange to maintain the bolt in the proper
longitudinal position while permitting the bolt to pivot. An
operator employing a screwdriver may rotate the bolt 35 about its
own axis from the exterior of the instrument to thus effect an
important adjustment as described below. The adjustment is effected
without providing an opening through which dirt, etc., may enter
the recess 13.
A link 49 is connected at one end to the second-class lever 35 and
at the other end to a first-class lever 50 (FIG. 5) which, in turn,
is connected to a guitar string 51 the pitch of which is to be
changed. The link 49 is disposed in recess 13 parallel to the
string 51, that is to say, generally in line with the neck 11.
Incorporated in link 49 is a turnbuckle having an
internally-threaded body 52 into which is threaded an
externally-threaded element 53 to which a loop 54 of hardened wire
is rigidly secured. The loop 54 extends snugly around the
second-class lever bolt 35 in such manner that the position of the
loop along the bolt 35 may be adjusted by turning such bolt. Thus,
the wire loop is threadedly related to the bolt. This provides an
extremely simple, economical and mass-producible manner of shifting
the connection between the link and the bolt, in response to an
operator employing a tool at the external portion of the mechanism,
whereby relative pivotal movement between the link 49 and the
second-class lever 35 is permitted. Stated otherwise, loop 54 forms
a highly effective nut and pivot element which is threadedly
related to the bolt 35, and which may pivot relative to the bolt as
shown in FIGS. 2 and 3.
Another externally-threaded element, numbered 56, is threadedly
associated with turnbuckle body 52, being connected with a loop 57
which is removably hooked around the lower end of the first-class
lever 50 for operation thereof. A spring 58 is jammed around
element 56, and around a portion of body 52, to prevent undesired
rotation of these elements relative to each other.
A cover plate 59 is mounted over the portion of recess 13 in which
the link 49 and the lever ends are disposed, being secured in
position by screws which are indicated generally at 61 in FIGS.
1-2. Such plate 59 has access openings 62 (FIGS. 1, 5 and 7)
therein, there being one such opening beneath each of the six
strings of the guitar.
There are six levers 50, one for each string, each such lever being
mounted in its own opening 63 through body 10 (such lever openings
communicating with recess 13). Each lever also extends through an
opening in a bridge plate 64 (FIGS. 5 and 7) which is secured by
suitable screws (not shown) to the face of body 10 and over the
openings 63. The upper end of each lever 50 is notched at 66 to
receive a portion of the bridge plate 64, so that a fulcrum is
provided at 67 (FIG. 5) for pivoting of the lever.
A guitar string extends upwardly through a bore 69 in each lever
50, being prevented from movement through the bore by an eyelet or
ball 70 at the end of the string. The string extends over a rounded
edge 71 of the associated lever and then over an adjustable bridge
element 72, which, in turn, is mounted on the bridge plate 64 by a
bolt 73. The bolt 73 extends through a flange 74 in the bridge
plate, there being a spring 76 provided between the flange and the
bridge element.
With the described construction, the guitarist may select which
string to pull by merely hooking the loop 57 over the desired one
of the six first-class levers 50. A helical compression spring 77
is mounted in each recess or opening 63 and is seated on the edge
of the lever which is closest to neck 11. Such spring insures that
the lever 50 will be in the proper position at all times, despite
string breakage. Such spring also insures that those levers not
associated with loop 54 will remain in proper positions for
anchoring of the associated strings.
It is highly important to the pitch-changing device shown in U.S.
Pat. No. 3,512,443, and in the present instrument, that the tension
on the string 51 will not change until a change is intentionally
effected by the guitarist. Thus, for example, the tension on the
string cannot be permitted to change as a result of the weight of
the guitar as it merely hangs from its strap 32. It is, therefore,
essential that a spring means be provided to maintain operating arm
18 in a predetermined position, despite the weight of the
instrument, and until the operator intentionally creates a relative
pull between the strap 32 and the instrument to thereby
intentionally elongate the string 51. The "predetermined position"
is the one shown in FIGS. 1 and 2, the bolt 26 then being
relatively remote from upper edge 29 (FIG. 1) of the body 10.
The present mechanism incorporates a simple, economical and compact
spring means which is very easy to assemble with the remaining
parts, and which does not exert any strain on the pivot bolt 19 for
the bell-crank. In the present mechanism, the spring means is a
helical torsion spring 78 which is wrapped around the oversize nut
21 and is maintained on such nut by a flange 79 at the upper
surface thereof. One end 78a of the spring extends toward the head
12 of the guitar and seats in an annular groove 81 in the oversize
nut 28. The other end 78b of the spring extends generally parallel
to such one end and seats in an annular groove 82 in a nut 83 which
is secured in recess 13 on the interior surface of plate 16 by
means of a bolt 84 (FIG. 4). Thus, the overall configuration of the
spring is in the nature of a hairpin.
The spring ends are seated on the sides of the nuts 83 and 28 which
are relatively adjacent each other (FIG. 2), and the manner of
winding of the spring is such that the natural tendency of the
spring is to cause the angle between the spring ends 78a and 78b to
increase. Thus, and since the nut 83 is fixed in position on plate
16, the spring normally forces the nut 28 and the bell-crank lever
and arm 18 to that end of slot 27 (the above-stated "predetermined
position") which is lowermost when the guitar is in the playing
position.
As shown in FIG. 4, the arms 78a and 78b of spring 78 are disposed
at different elevations. Furthermore, the nut 28 is much shorter
than the nut 83, the relationship being such that the nut 28 may
move beneath spring arm 78b when the mechanism is shifted to the
actuating position shown in FIG. 3.
It is pointed out that both of the levers 22 (including operating
portion 18) and 35 pivot in a plane which is generally parallel to
guitar body 10, that is to say, is generally parallel to the face
and back of such body.
MANNER OF ASSEMBLY, AND OPERATION
The device is very simple to assemble, by first inserting the bolt
84 through the plate 16 and then securing the stop nut 83 in
position. The bolt 19 is then inserted through arm 18, plate 16,
bushing 23 and arm 24, following which the nut 21 is mounted over
the bolt 19 after first being passed through the helical torsion
spring 78. The bolt 26 is inserted through slot 27, and through arm
24, following which nut 28 is mounted into position. It is then a
highly simple matter to snap the ends of the spring arms 78a and
78b into the annular grooves 81 and 82 in the nuts 28 and 83.
The second-class lever bolt 35 is inserted through the oversize
opening 38 (FIG. 6) and then through flange 44, after first being
passed through the loop 54. The nut 46 and spring 47 are then
mounted on the end of the bolt.
The assembly formed by the plate 16 and associated elements is then
secured to the guitar body 10 over the L-shaped recess therein. The
levers 50 are then inserted through openings 63 and through bridge
plate 64, springs 77 are inserted (FIG. 5), and the loop 57 is
hooked over the lever 50 associated with the string 51 which it is
desired to tension.
The lower end of each lever 50 is biased by its associated spring
77 against the wall of opening 63 which is remote from the neck 11.
All of the levers 50 remain in such position, except the lever
which is connected to link 49 and thus to the above-described
pitch-changing mechanism.
The loop 54 is initially associated with a midportion of lever bolt
35, as shown in FIGS. 2 and 3. Furthermore, the turnbuckle
incorporated in link 49 is so adjusted (at the factory) that, prior
to pulling on strap 32, the associated lever 50 is spaced away from
the wall of opening 63 (against the bias of spring 77). Thus, even
when the mechanism is in the condition of FIG. 2, the string
tension is determined by the engagement of bolt 26 with the end of
slot 27. There is no play or lost motion in the entire
mechanism.
The operator then tunes the string 51 to the desired base pitch, by
turning one of the tuning pegs (not shown) on head 12. This is done
prior to pulling on strap 32, the mechanism still being in the FIG.
2 position. The operator then actuates the operating arm 18 to the
extreme position permitted by the slot 27. Stated otherwise, the
mechanism is shifted to the actuated position of FIG. 3.
Thereafter, the lever bolt 35 is rotated about its longitudinal
axis to shift loop 54 therealong until the tuning of the string 51
is as desired, being normally one-half tone above the tuning of the
string when the mechanism is in the FIG. 2 position. The mechanism
is then relaxed to the FIG. 2 position, and the base-pitch tuning
is again adjusted by turning the tuning screw on head 12. The
above-described sequence is, if necessary, repeated until both the
base pitch and the elevated pitch are precisely as desired by the
musician.
The cover 59 is mounted at the factory, after all factory
adjustments have been made. If necessary, and without removing
either the plate 16 or the cover plate 59, pitch adjustments may be
made (by the musician) in the upper pitch to which the string is
tuned when the mechanism is in the actuated position of FIG. 3.
This is done by merely rotating the bolt head 37 (FIG. 6), with the
mechanism in the actuated position, until the desired pitch is
achieved. As described above, the base pitch is determined by the
tuning screw on head 12. Cover 59 is not normally removed unless
and until the musician desires to hook loop 57 over another lever
50.
When a string breaks, a new one is threaded through hole 62 (FIG.
5) and bore 69 and then extended over bridge element 72.
EMBODIMENT OF FIGS. 8 and 9
In the embodiment of FIGS. 8 and 9, parts which correspond to those
of the previous embodiment have been given the same reference
numerals. In addition, reference characters which generally
correspond have been given the same reference numerals as in the
previous embodiment, except followed by the letter a or b. The
operation and construction of the embodiment of FIGS. 8 and 9 are
identical, except as specifically stated, to the operation and
construction of the embodiment of FIGS. 1-7.
In the embodiment of FIGS. 8 and 9, the recess 39 (FIG. 6) in the
plate 16a is made sufficiently large to receive the heads of two
lever bolts 35a and 35b, which bolts extend through the flange 44a
at the end of bell-crank arm 25a. Two turnbuckles or links 49a and
49b are provided, and are respectively associated with the lever
bolts 35a and 35b. Thus, two of the levers 50 may be associated
with the present mechanism, thereby permitting two strings 51 to be
pulled instead of a single string.
Referring particularly to FIG. 9, it is pointed out that the loop
54a extends downwardly over bolt 35a, whereas loop 54b extends
upwardly around bolt 35b. Thus, the loops 54a and 54b may be spaced
away from each other in order to prevent interference therebetween
as a result of turning of the respective bolts 35a and 35b.
The head of bolt 35 is provided with suitable slot means (for
example of the Phillips type) adapted to receive the tip of a
screwdriver.
A "second-class lever" is one wherein the fulcrum is at one end,
the force is applied at the other end and the load (resistance) is
in the middle. A "first-class lever" is one wherein the fulcrum is
in the middle.
The foregoing detailed description is to be clearly understood as
given by way of illustration and example only, the spirit and scope
of this invention being limited solely by the appended claims.
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