Tremolo bridge for guitars

A tremolo plate is pivotally mounted on the guitar body, and a plurality of a combination bridge saddles and lever systems are mounted on such plate, there being one such saddle-lever system for each string of the guitar. The combination systems include saddles adapted to be pivoted by set screws to change string height. They further include levers adapted to be adjusted by screws to effect fine tuning of the strings. The heads for the fine tuning screws are captured by ears. The pivot means for the tremolo plate have a pivot axis so related to the string saddles that the intonation points of the saddles may be adjusted between positions closer to the guitar neck than is such axis, and positions farther from the guitar neck than is such axis.

BACKGROUND OF THE INVENTION 
It is highly desirable, in a tremolo apparatus for an electric guitar, to 
have not only fine tuning but also individual string-height adjustment. 
Furthermore, it is important to achieve these and other results with a 
tremolo that is so flat on the upper side thereof, regardless of the 
positions of the fine-tuning elements, that the musician may, when he 
wishes, rest his hand or forearm on the tremolo. This is particularly true 
when the tremolo is one having a removable arm and which is capable of 
being locked during periods when no tremolo operation is desired. 
The tremolo must be such that the various strings will remain on the 
intonation points even when the tremolo plate is pivoted or tilted 
upwardly to an extreme position. Otherwise, the tuning of the instrument 
would be lost during such intervals of extreme tilt-up. 
Because of the frequent tendency of guitarists to bend strings in order to 
achieve sounds somewhat like those generated by a pedal guitar, it is 
important tht such bending produce little or no effect in the strings not 
bent. In other words, there should be little or no cross talk between the 
strings, even when very strong bending operations are occurring. 
An additional factor, that has been recognized since tremolos for electric 
guitars were originated, is that the tremolo must return to its initial or 
"zero" position after the musician releases the tremolo arm. For this to 
occur, friction in the tremolo apparatus must be reduced to the 
lowest-possible amount commensurate with ruggedness and 
mass-producibility. 
SUMMARY OF THE INVENTION 
In the present tremolo apparatus, the pivot axis is relatively far from the 
neck of the guitar, so far that longitudinally-adjustable saddles on the 
tremolo plate may be shifted forwardly to positions at which the 
intonation points are closer to the neck than is the pivot axis. 
Furthermore, the pivot axis is high, being only a very small distance 
below the intonation points. Because of the stated positioning of the 
pivot axis, even very strong bending of a string does not generate a 
torque sufficient to effect any substantial pivotal movement of the 
tremolo plate. The plate therefore stays substantially steady, unless 
intentionally operated by the guitarist for tremolo action. In addition, 
pivotal movement of the plate does not cause a large amount of lifting of 
the intonation points, because when viewed in plan the intonation points 
are generally in line with the pivot axis, it being understood that the 
intonation points are adjustable both forwardly and rearwardly in order to 
achieve proper intonation of the strings. 
In accordance with another aspect of the present invention, there is 
individual string-height adjustment by rotation of saddle elements about 
horizontal axes, in combination with fine tuning caused by pivoting of 
levers. Such fine tuning is preferably about the same axes as are employed 
for the string-height adjustment. 
In accordance with another aspect of the invention, means are provided on 
the sides of the intonation points relatively remote from the neck to 
cause the strings to bend down closely adjacent the intonation points, the 
result being that even when the bridge plate is tilted upwardly to an 
extreme position, the strings remain in firm engagement with the 
intonation points as is necessary to prevent loss of the tuned condition 
of the guitar during these intervals. 
For fine tuning, levers are tilted by means of screws that do not rotate, 
adjustment instead being effected by captive screw heads the upper 
surfaces of which are flat and always remain at the same elevation. These 
screw heads therefore provide, in combination with the saddles, which are 
relatively flat on the upper sides thereof, locations on which the 
guitarist may confortably rest his hand or forearm. 
The pivot axis is formed by short but straight knife-edge elements, which 
cooperate with pivot blocks that are spaced apart and between which 
forward portions of the bridge plate and saddles project. This minimizes 
friction while achieving a high degree of wear resistance.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The present tremolo apparatus is incorporated in a conventional guitar 
having a body, a neck projecting from one end of the body, and guitar 
strings provided over the neck and body. An early classic guitar of this 
type is illustrated, except for the neck, in Fender U.S. Pat. No. 
2,741,146, which is hereby incorporated by reference herein. The guitar 
and guitar neck are shown in U.S. Pat. No. 4,206,679, which patent also is 
hereby incorporated by reference herein. However, instead of having the 
nut shown in U.S. Pat. No. 4,206,679, it is preferred that the present 
guitar incorporate a locking nut. The preferred nut is described and 
illustrated in U.S. patent application Ser. No. 697,220, filed on even 
date herewith, for a "Clamping Nut and Method", inventors Gressett and 
Page. 
The guitar body is shown fragmentarily at 10, and has a recess provided in 
the upper side thereof in order to receive portions of the tremolo 
apparatus, particularly the tremolo spring and associated lever arms and 
spring-adjustment means. 
Pivot blocks 11 (that are identical to each other, except that they are 
left and right) are mounted on suitable lands in the recess in body 10, 
and anchored by means not shown. As best illustrated in FIG. 6, the pivot 
blocks 11 have V-grooves 12 in the rear sides thereof (the sides most 
remote from the neck of the guitar). Each V-groove 12 has inserted therein 
a knife edge 13 as shown in FIGS. 6 and 7. The two V-grooves 12 are in 
exact alignment with each other along a line perpendicular to the guitar 
strings. Correspondingly, the two knife edges 13 are in exact alignment 
with each other, so that the knife edges and V-grooves cooperate to form 
the pivot axis or fulcrum for the tremolo apparatus. 
The spaced-apart knife edges are straight but are short, for example, each 
is one-quarter inch long. The described elements produce very low-friction 
but rugged pivotal elements characterized by the ability to withstand much 
wear. It is pointed out that the use of the word "knife" does not imply 
such sharpness as to be able to cut most objects, and edges actually being 
in the nature of dull knives. 
Referring to FIGS. 1 and 6, the pivot blocks 11 are disposed on opposite 
sides of a forwardly-projecting portion 16 of a tremolo plate 15. Stated 
otherwise, the forward portion of plate 15 extends between and adjacent 
the pivot blocks, there being sufficient cleaarance provided to prevent 
any drag on the pivotal movement. 
As best shown in FIG. 1, the illustrated tremolo plate 15 has a relatively 
wide portion remote from the neck of the guitar. At the forward and outer 
regions of such wide portions there are provided the knife elements that 
define knife edges 13. 
Preferably, the two pivot blocks 11 are connected by a cross-element that 
extends therebetween and is preferably integral therewith. The 
cross-element extends below the tremolo plate, and is numbered 17 in FIG. 
6. Furthermore, centering pins (not shown) are provided at the outer end 
of each V-groove to confine the sides of the knife edges 13, and prevent 
any rubbing between the tremolo plate and pivot blocks. 
There are provided on both the narrow forward portion 16 of tremolo plate 
15, and the wider rear portion of such plate, a plurality of combination 
lever systems and bridge saddles. Such combinations are numbered 18, and 
each is identical to the others except that--preferably--those on opposite 
sides of the central vertical plane of the guitar are "left" and "right" 
for symmetry of appearance. There being six guitar strings, there are six 
combination bridge saddle and lever systems 18, the three on one side of 
the vertical central plane of the guitar being mirror images of the three 
on the other side thereof. 
Only one such saddle, being the third from the top in FIG. 1, will be 
described in detail because of the substantial identity of shapes and 
functions. Such saddle is shown in enlarged form in FIGS. 2, 3 and 7. 
Referring first to FIGS. 2 and 3, the forward portion of each combination 
bridge saddle and lever system 18 (the portion closest to the neck of the 
guitar, and shown at the left) is a longitudinally adjustable, clampable, 
saddle block 21 having a string saddle 22 pivotally mounted therein for 
rotation about a horizontal pin 23. Such pin 23 is parallel to the pivot 
axis of the tremolo plate. 
The saddle block 21 is recessed in its forward portion to receive the head 
of a clamping bolt 25, such bolt extending downwardly through a 
longitudinal slot 26 in tremolo plate 15 so that the saddle block and 
associated elements may be adjusted longitudinally of the guitar strings. 
The head of bolt 25 has an internal hex socket, and a nut 27 is provided 
beneath the tremolo plate so as to permit locking of the saddle block 21 
in the correct longitudinal position for proper string intonation. 
String saddle 22 has a grooved upper portion 28 (FIG. 2) adapted to seat 
one of the guitar strings 29 (FIGS. 3 and 7). The elevation of the string 
is determined by the rotated position of saddle 22 about pin 23, the pin 
23 being eccentrically mounted relative to the upper saddle portion. To 
determine the rotated position, a set screw 31 is provided in the saddle 
block 21, and bears downwardly on a crank portion 32 of saddle 22 (FIG. 
3). 
It is pointed out that, as shown in FIG. 3, the intonation region, that is 
to say, the highest region, of the saddle 22--on which the string 29 
actually seats--is toward the rear of the saddle, namely the right thereof 
as shown in FIGS. 3 and 7. Thus, the downward pressure exerted by string 
29 on the saddle tends to pivot the saddle clockwise about pin 23, which 
causes crack 32 to press upwardly against the lower end of set screw 31. 
Accordingly, the indicated clockwise pressure maintains the crank 32 
against the sew screw at all times when the guitar is strung, so that 
rotation of the set screw 31 in either direction (by a suitable wrench 
inserted into a socket hole at the upper end of the set screw) effects 
precise elevational adjustment of each individual guitar string. 
The location of the intonation point at the rear of saddle 22 provides a 
further desirable effect in cooperation with a hold-down portion 34 of a 
lever 35. As best shown in FIGS. 1 and 2, the forward end of lever 35 is 
bifurcated and fits between ears 36 that project rearwardly from the main 
body of saddle block 21. The saddle 22, in turn, fits into the bifurcated 
forward end of the lever 35. 
Lever 35 is pivotally associated with the same pin 23 that mounts the 
saddle element 22. 
The above-indicated hold-down portion 34 is integral with lever 35 and 
extends laterally from one side 37 thereof, reference being made to FIG. 
2. The portion of the lever beneath hold-down 34 is void, there being 
laterally-projecting elements 38 and 39 to the front and rear of the void 
beneath the hold-down (FIGS. 2, 3 and 7). 
The hold-down 34 is preferably generally triangular in section, with its 
base at the top. It is disposed sufficiently far forwardly, and is 
sufficiently deep, that the string 29 after passing over saddle 22 in 
grooved portion 28 will bend downwardly at a angle sufficient to insure 
firm engagement between the string and saddle regardless of the pivoted 
position of the tremolo plate. Reference is made to FIG. 7, which shows an 
upward-pivoted position of the tremolo plate 15. 
After passing beneath hold-down 34, the string 29 bends upwardly over the 
laterally-projecting element 39 in a groove 40 therein (FIG. 2). Then, the 
string passes downwardly through a notch 41 (FIG. 2) and into a ball-end 
seat 42. The notch and seat 41 and 42, respectively, open laterally, being 
so constructed that--in association with groove 40--the harder the string 
29 is tensioned the more firmly the ball end at the end of string 29 seats 
in its seat 42. 
To achieve fine tuning of each individual guitar string that passes over 
the height-adjustment saddle 22, means are provided to pivot each lever 35 
about pin 23 without disturbing the substantially flat and uniform 
condition of the upper portion of the tremolo apparatus. Thus, regardless 
of the fine tuning, the entire upper portion of the tremolo may serve as a 
seat or rest for the hand or forearm of the guitarist. 
Referring to FIGS. 3 and 5, each combination bridge saddle and lever system 
18 includes a screw head 43 the upper surface 44 of which is flat and low. 
Screw head 43 has an annular groove 45 at the lower portion thereof, which 
groove 45 receives ears 46 (FIG. 5) on plate 15 that hold the screw head 
43 captive. It is emphasized that FIG. 5 is a view looking from the tail 
of the guitar toward the neck thereof, that is to say, toward the left in 
FIGS. 1 and 3. 
Threadedly associated with each screw head 43 in a screw 47. The screw 47 
extends downwardly through an unthreaded bore in tremolo plate 15 and 
bears downwardly against the upper surface of a tail portion 52 of the 
lever 35. As best shown in FIG. 3, such tail portion 52 is disposed 
beneath the rear region of the tremolo plate 15. 
Referring to FIG. 4, the screw 47 is not cylindrical but instead has a flat 
or key portion 53 that prevents it from rotating in the tremolo plate. 
Stated otherwise, the bore in the tremolo plate 15 is D-shaped, and a 
D-shaped screw fits vertically-slidably therein. 
To maintain each lever 35 in upwardly-bearing engagement with the bottom of 
screw 47, a helical compression spring 54 is seated between the underside 
of tail 52 and a spring seat in a plate 56 illustrated in FIGS. 3 and 7. 
The plate 56 extends forwardly and is connected to the underside of 
tremolo plate 15, being between two cranks or arms 57. There is one such 
arm 57 on each side of the tremolo plate and connected thereto. 
Connected to each crank or arm 57 is a helical tension spring 58 (FIG. 3) 
that extends forwardly and is anchored within the body 10 of the guitar. 
For a detailed description of the springs 58 and associated 
spring-adjustment mechanism, reference is made to patent application Ser. 
No. 697,219, filed on even date herewith, for a "Tremolo Spring Adjustment 
Mechanism for Electric Guitars", inventor Gressett. The springs 58 
counteract the tension of strings 29 to create a floating relationship, so 
that the tremolo plate remains stationary except when intentionally 
actuated by a guitarist pressing on the tremolo arm 60 (FIG. 1). 
Tremolo arm 60 is removably secured to plate 15 as described in copending 
patent application Ser. No. 689,715, filed Jan. 4, 1985, for "Snap-End 
Vibrato Arm", inventors Page and Schaller. The tremolo arm has wrenches in 
opposite ends thereof, one fitting within a handle that screws onto the 
outer end of the arm, the other projecting downwardly from a portion of 
the arm 60 that is within the guitar body. Such wrenches are externally 
hex-shaped and seat into the various socket holes in set screw 31, clamp 
bolt 25 etc., to operate the same after the arm has been snapped out of 
its socket. One of such wrenches, the one at the lower end of the arm 60 
(within the guitar body when the arm is in playing position) is shown in 
said application filed on even date for a "Tremolo Spring Adjustment 
Mechanism for Electric Guitars", inventor Gressett. 
Referring again to the tremolo axis for plate 15, this is both relatively 
far rear (to the right of FIG. 1) and very high in comparison to the 
length of the cranks or arms 57. There is a very short torque arm or 
moment arm between string 29 and the pivot axis for tremolo plate 15 when 
the plate is not actuated, that is to say, is in the balanced or floating 
position of FIG. 3. Because of this high mechanical advantage that the 
spring 58 has relative to the moment created by each string 29, even 
strong bending of a string 29 does not tend to effect any substantial 
pivoting of the tremolo plate away from its balanced position. Thus, there 
is little or no cross talk between the strings even during bending of one 
or more of the strings. 
Stated in positive terms, the moment arm of the spring, relative to the 
pivot axis of the tremolo plate, is at least nine times that of the 
strings, when the plate is floating (not actuated). 
Referring particularly to FIG. 1, it is pointed out that the slots 26 etc., 
are so located that the individual elements 18 may be adjusted very far 
forwardly, so far forwardly that the intonation point on saddle 22 is 
sometimes forward of the pivot axis of the tremolo plate as viewed in FIG. 
1. Others of the intonation points are at the axis as viewed in FIG. 1, 
while others are behind it. The location of the intonation points near the 
axis, as viewed in plan (FIG. 1), creates a relationship by which tilting 
of the tremolo plate by pressing on arm 60 creates less elevation of the 
intaonation points when the arm 60 is depressed (and tremolo plate 15 
accordingly pivotally upwardly from the FIG. 3 position to that of FIG. 
7). 
There has thus been described a tremolo apparatus incorporating both 
individual string-height adjustment, and fine tuning. One that creates 
minimized cross talk between the strings, and stays flat for hand support 
no matter what the setting is for fine tuning. The strings may not lift 
off the intonation points even when the plate pivots upwardly very far, 
and friction is minimized so that the plate returns accurately to zero 
position. 
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.