Tilt indicating device

A tilt indicating device mountable on a tiltable vehicle or machine component and operable to close an electrical circuit to thereby give an audio/visual warning or initiate levelling action in case of tilt. The device comprises an insulated housing having a chamber therein filled with electrically non-conductive viscous damping fluid in which a float is submerged and upwardly bouyed. An electrically conductive ball and socket pivot assembly connects the float to the chamber floor and enables tilting of the housing relative to the float in any direction from vertical. An electrically conductive circular disc horizontally mounted on the float stem and electrically connected through the pivot means to a connector terminal on the exterior of the housing is spaced from but engageable during tilt with the upper edge of an annular collector ring mounted on the housing floor and surrounding the pivot means. The collector ring which may include either a continuous electrical conductor (for indicating a predetermined degree of tilt in any direction) or a plurality of conductive segments insulated from one another (for indicating the direction as well as degree of tilt) is electrically connected to a connector terminal or terminals on the exterior of the housing. An air-filled fluid expansion chamber in the housing connects to the fluid chamber. The pivot assembly is vertically adjustable from the exterior of the housing to change the spacing between the disc and collector ring and thereby determine the tilt angle necessary for contact closure. A spirit level, adjustable levelling screws and mounting means are provided on the housing.

BACKGROUND OF THE INVENTION 
1. Field of Use 
This invention relates generally to tilt indicating devices for mounting on 
tiltable vehicles or tiltable machine components and to control systems 
employing such devices. 
2. Description of the Prior Art 
Tilt indicating devices are used on off-the-road or rough-terrain vehicles 
to sense when the vehicle, or some movable component thereon, has reached 
a potentially dangerous tilt angle. Some such devices provide a direct 
visual indication of tilt so that appropriate corrective action can be 
taken by the machine driver or operator, while others are connected in 
control systems which either provide an audio/visual indication of tilt or 
effect levelling of the tilted vehicles or component. For example, when 
operating agricultural or construction machinery on a hillside, it is 
important that the vehicle itself not exceed a cetain tilt angle so as to 
prevent roll-over. Similarly, when operating vehicles such as cranes or 
fork-lift trucks which have tiltable components, such as booms or masts, 
respectively, it is important that the component not exceed a certain tilt 
angle to prevent vehicle imbalance and possible tip-over. 
The prior art discloses many examples of mechanical and electromechanical 
slope or tilt indicating devices which give a direct read-out or which are 
employed in control systems which provide a read-out or a control 
function. For example, U.S. Pat. No. 3,377,714 discloses a device wherein 
an inverted pendulum type upright float is mounted for pivotal movement 
about a single axis in a liquid medium and gives a mechanical visual 
readout. U.S. Pat. No. 3,559,294 discloses a device wherein a float on the 
surface of a liquid tilts about a single axis and operates a potentiometer 
to give an electrical readout. U.S. Pat. No. 3,660,840 discloses a device 
wherein a float on a liquid surface makes electrical contact with four 
electrical contacts carried at the four corners of a cross-shaped member 
fixed to the reservoir. Each contact actuates a particular light to 
thereby indicate one of four possible directions of inclination. U.S. Pat. 
No. 2,772,411 discloses a device wherein a pendulum in liquid pivots about 
a single axis and operates a variable resistor to serve as a boom angle 
indicator for cranes. U.S. Pat. No. 3,945,391 discloses a device wherein a 
float immersed in liquid rotates about a single axis to operate a valve 
serving as a boom leveler. U.S. Pat. No. 3,865,265 teaches a device for 
electrically determining the direction and degree of tilt of the mast of a 
forklift truck and employs a pendulum immersed in liquid and swingable 
about a single axis which operates a potentiometer. U.S. Pat. No. 
3,846,781 teaches a device wherein there is a pendulum and pointer 
swingable about a single axis for slope measurement and makes provision 
for actuating electrical contacts in response to pendulum movement. U.S. 
Pat. No. 3,805,398 teaches a pivotally mounted freely rotatable magnet 
which serves as an angle sensor for a drilling tool for earth boring. The 
magnet position determines energization of sensing coils which effect a 
readout. 
SUMMARY OF THE INVENTION 
In accordance with the invention, there are provided several embodiments of 
a tilt or slope indicating device which are adapted for mounting on a 
tiltable vehicle or a tiltable machine component. Also provided are 
several control systems for employing such devices and whereby either 
electrical audio/visual warning devices or machine or component levelling 
devices are actuated. 
A tilt indicating device in accordance with the invention generally 
comprises a housing connectable in level position on a tiltable vehicle or 
component and having a chamber therein; a float located in the chamber; 
pivot means for pivotally connecting the float to the housing to enable 
relative pivotal mount of the float when the housing is tilted in any 
direction; electrically non-conductive high-viscosity damping liquid in 
the chamber and in which the float is submerged at least to the extent 
that float buoyancy maintain a positive upward force at the pivot means; 
first and second spaced apart electrical contact members in the chamber 
connected to the float and to the housing, respectively, and electrically 
inter-engageable with each other when the housing is tilted a 
predetermined degree in any direction; and electrical terminals located 
externally of the chamber and electrically connected to the first and 
second electrical contact members, respectively. 
The first electrical contact member preferably takes the form of a circular 
disc which extends transversely to and radially outwardly from the tilt 
axis of the float. The second electrical contact member takes the form of 
an annular collector ring surrounding the tilt axis of the float and, 
preferably, secured at or near the floor of the housing. In one 
embodiment, the annular ring comprises a substantially continuous 
electrically conductive member. In another embodiment, the annular 
collector ring comprises a plurality of electrically conductive segments 
which are electrically insulated or spaced apart from each other. 
In a preferred embodiment of the invention, the pivot means for pivotally 
connecting the float to the housing comprises a ball and socket joint, 
including first and second electrically conductive pivot members 
mechanically connected to the float and to the housing, respectively, and 
pivotally interconnected with each other and the float buoyancy upward 
force maintains positive electrical contact between the ball and socket 
pivot members. 
Furthermore, in a preferred embodiment, the first electrical contact member 
or disc is connected to the float for movement therewith by being 
electrically and mechanically connected to the first electrically 
conductive pivot member. 
Adjustment means are provided for adjusting or changing the distance at 
which the first and second electrical contact members are spaced apart 
from each other to thereby adjust or change the predetermined angle to 
which the housing of the device must be tilted to ensure contact 
engagement. Preferably, such adjustment means comprise an adjustment screw 
accessible from the exterior of the housing for raising and lowering the 
pivot means to thereby effect corresponding movement of the disc relative 
to the collector ring. 
Means are provided on the housing for initially adjusting or levelling the 
device relative to the tiltable vehicle or component and preferably take 
the form of a plurality of threaded legs movably attached to the housing 
and engageable with a surface on the vehicle or component on which the 
housing is mounted. 
Means are also provided on the housing to initially ascertain or establish 
when the device is level and such means comprise an omni-direction bubble 
type or spirit level attached to or integral with the housing. The damping 
liquid is non-freezeable and one or more expansion chambers communicate 
with the chamber containing the liquid so as to provide a means to 
accommodate expansion and contraction of the liquid in response to ambient 
temperature changes. 
The said one embodiment of the tilt device in which the collector ring 
comprises a substantially continuously electrically conductive member is 
connectable in series circuit with an electrical power source, such as a 
battery, and an electrically operable audio or visual warning device or 
alarm. The said other embodiment wherein the collector ring comprises 
electrically discrete segments is connectable in a control circuit of a 
type wherein each segment is in series circuit with an electrical power 
source and an electrically operable individual warning device. Or, the 
said other embodiment is connectable in a control circuit of a type 
wherein each segment operates a relay or solenoid valve, for example, 
which effects levelling of the vehicle or component. 
In operation, when the vehicle or component on which the tilt indicating 
device is mounted is level or upright, the housing is also upright, and 
the tendency of the float to remain vertical maintains separation between 
the first and second contact means. However, when the housing tilts in any 
direction from vertical in response to corresponding tilting movement of 
the vehicle or component, the tendency of the stem attached to the float 
to remain vertical causes some portion or side of the upper edge of the 
collector ring to engage the underside of some portion of the disc thereby 
establishing electrical contact therebetween. In the said one embodiment, 
such contact, regardless of the direction of tilt, causes a single or 
common warning device, such as a light or buzzer, to be actuated, 
indicating that a tilt of some predetermined degree has been reached. In 
the said other embodiment, contact between the disc and one particular 
segment of the collector ring either causes a particular warning device to 
be actuated, indicating that a tilt of some predetermined degree and in a 
specific direction had been reached, or causes an appropriate levelling 
device, such as a hydraulic cylinder to be actuated to effect levelling of 
the tilted machine or component. 
A tilt indicating device in accordance with the invention offers several 
advantages over the prior art. For example, the device is adapted for use 
with any type of tiltable vehicle, structure or component on which it can 
be physically mounted. The use of non-freezable damping liquid and 
provision of an air-filled expansion chamber therefor enables the device 
to be used and operate reliably in extremely hot or cold ambient 
temperatures. The device is responsive to tilting in any direction from 
the vertical and is not limited to tilting in a single plane or in only 
two transverse directions. The device can, furthermore, be adapted by use 
of the segmented collector ring to provide an indication of the direction 
of tilt, as well as the degree or extent of tilt or to provide appropriate 
corrective levelling. The sensitivity of the device, i.e., the degree or 
amount of tilt necessary to cause it to actuate its associated warning 
device or devices, can be changed or adjusted to suit particular operating 
circumstances and such change or adjustment can be accomplished from the 
exterior of the housing, without the need for disassembly of the device, 
by means of a simple tool such as a screw-driver. The use of a relatively 
high viscosity damping fluid and the use of upwardly acting positive 
floatation forces reduces the sensitivity of the device to transient 
tilting or bumps. The device is relatively simple in principle of 
operation and construction, economical to manufacture, reliable and 
versatile in use, and quickly and easily adjusted in the field. Other 
objects and advantages of the invention will hereinafter appear.

DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring to FIGS. 1, 2 and 3, numeral 10 designates a tilt indicating 
device which is mountable on structural member 16 of a tiltable vehicle or 
machine component (not shown) and which is operable to close an electrical 
circuit to thereby give an audio/visual warning or initiate levelling 
action in case of tilt. The device 10 comprises an insulated housing 12 
having a liquid chamber 24 therein filled with electrically 
non-conductive, non-freezable viscous damping liquid 26 in which a float 
60 is submerged and upwardly bouyed. An electrically conductive ball and 
socket pivot assembly 13, including a ball 66 and a socket 68, connects 
the float 60 to the chamber floor or base plate 20 and enables tilting of 
the housing 12 relative to the float in any direction from a vertical axis 
X (see FIG. 9). An electrically conductive circular disc 65 horizontally 
mounted on a float stem 62 and electrically connected through the pivot 
assembly 13 and pin 74 (FIG. 7) to a connector terminal 41E on the 
exterior of the housing 12 is spaced from but engageable during tilt with 
the upper edge of an annular connector ring 40 mounted on the housing 
floor 20 and surrounding the pivot assembly 13. As FIGS. 2, 4 and 10 show, 
the collector ring 40 includes a plurality of conductive segments 41A, 
41B, 41C and 41D which are insulated from one another and provide for 
indicating the direction as well as the degree of tilt. These segments are 
electrically connected to a plurality of connector terminals 71A, 71B, 71C 
and 71D, respectively, on the exterior of the housing 12. As FIG. 11 
shows, in an alternative embodiment, a collector ring 40A is provided and 
comprises a continuous electrical conductor for indicating a predetermined 
degree of tilt in any direction. An air-filled fluid expansion chamber 34 
in the housing 12 connects to the liquid chamber 24. The pivot assembly 13 
is vertically adjustable from the exterior of the housing by means of a 
screw 74 to change the spacing between the disc 65 and collector ring 40 
and thereby determine the tilt angle necessary for contact closure. A 
spirit level 81, adjustable levelling screws 82 and a plurality of 
mounting nuts 83 are provided on the housing 12. 
As FIGS. 2 and 8 show, the device 10 is adapted for use with and for 
mounting in a fixed level position on structural member 16 of a tiltable 
vehicle (not shown) or on a tiltable machine component (not shown) by 
means of adjustable levelling and mounting bolts or screws 82. Chamber 24 
of housing 12 is completely filled with an electrically non-conductive 
non-freezable highly viscous damping liquid 26, such as "200 Fluid," a 
dimethylpolysiloxane having a viscosity of 10,000 C.S., and available from 
the Accumetric Division of Detrex Chemical Industries, P. O. Box 843, 
Elizabethtown, N. J. Housing 12 comprises an electrically non-conductive 
generally flat circular base plate or member 20, an electrically 
non-conductive generally flat circular top cover plate or member 22, and a 
hollow cylindrical or tubular intermediate member 18. The members 18, 20 
and 22 are preferably fabricated of plastic and are mechanically secured 
together in permanent leak-proof relationship by means of tie rods 21 and 
annular grooves 28 and 30 in the members 20 and 22, respectively, which 
receive the lower and upper ends, respectively, of tubular member 18. 
Preferably, the grooves 28 and 30 contain O-ring seals 28A and 30A, 
respectively. Cover plate 22 is provided with an internally threaded or 
tapped liquid fill port 32 extending therethrough, which port is sealable 
by means of a removable sealing screw 33. Cover plate 22 is also provided 
with the recess or expansion chamber 34 extending inwardly from the 
underside thereof, and preferably formed by drilling, in which air is 
entrapped when chamber 24 is filled with liquid 26. The trapped air in 
recess 34 is compressible and, therefore, recess 34 can accommodate some 
liquid 26 as the latter expands within sealed chamber 24 when device 10 is 
exposed to sufficiently high ambient temperatures, such as occur in direct 
sunlight on hot summer days. 
Base plate 20 is provided with a centrally located internally threaded bore 
or hole 36 therethrough in which an electrically conductive hollow 
cylindrical externally and internally threaded sleeve 37 is secured, which 
sleeve supports the adjustable pivot assembly 13 hereafter described in 
detail. Base plate 20 supports the hollow cylindrical or annular metal 
collector ring 40 which is secured thereto by suitable electrically 
conductive bolts 42. Holes 41 extend through base plate 20 and accommodate 
the electrically conductive bolts 42 which also make electrical contact 
with the lower flanged edge of each segment 41A-41D of ring 40. As FIGS. 
2, 4, 5, and 6 show, each bolt 42 is electrically and mechanically 
connected to an electrically conductive strap 44 which lies in a recess 45 
formed in the underside of base plate 20. Each strap 44 is electrically 
and mechanically connected to a connector terminal 71A-71D in the form of 
a threaded bolt 46 which extends through a hole 47 in base plate 20. Base 
plate 20 is provided with an electrically conductive strap 52 which lies 
in a recess 53 formed in the underside of base plate 20. Strap 52 is 
electrically and mechanically connected between sleeve 37 and connector 
terminal 41E. Terminal 41E comprises an electrically conductive threaded 
member 55 which serves as another terminal connector. 
As FIG. 2 shows, float 60 is immersed and bouyed up in the liquid 26, and 
takes the form of a hollow flexible sphere having a threaded sleeve 61 at 
its bottom. Float 60 is mechanically connected by sleeve 61 to the upper 
threaded end of elongated electrically conductive stem 62 which extends 
downwardly therefrom. The electrically conductive contact means in the 
form of circular metal disc 65 is electrically and mechanically connected 
to the lower externally threaded end of stem 62 by a pair of nuts 63 and 
is disposed above and spaced apart from ring 40 when device 10 is upright 
or untilted, as shown in FIG. 2. 
The electrically conductive pivot means or assembly 13 are provided for 
pivotally connecting the lower end of stem 62 (and thus the float 60) to 
the base 20 of housing 12. The pivot assembly 13 comprises a 
ball-and-socket joint which includes an internally threaded ball member 66 
which is an integral part of the externally threaded lower end of stem 62 
and a socket member 68 is engageable with the ball. Socket member 68 
comprises a socket or recess 69 for accommodating ball 66, an upper 
opening 70 for accommodating the portion of stem 62 connected to the ball, 
and internally threaded lower opening 72 for threadedly engaging the 
externally threaded upper end of a support and adjustment screw or pin 74. 
Pin 74 is screwed into the threaded sleeve 37 in base plate 20 of housing 
12 and serves as a means by which the pivot assembly is physically 
supported on the housing 12 and by which the pivot assembly (and the 
spacing between the contacts 40 and 65) are vertically adjusted. Pin 74, 
has a slot 75 for receiving the tip of a screw-driver (not shown) at its 
lower end. 
As hereinbefore mentioned, a spirit level 81 and adjustable levelling 
screws 82 are provided for initially establishing device 10 in a level (or 
other desired) position on framework 16. Spirit level 81 may take the form 
of a commercially available bubble type spirit level attached to the top 
of housing 12, as shown in FIG. 8, and, for example, a "Level All" device 
available from Reese, Elkhart, Ind., would be suitable. If preferred, the 
level 81 may be integrally formed in the housing 12 of the device 10, as 
shown in FIGS. 2 and 3. In the latter arrangement, cover 22 is transparent 
and an air bubble 81A trapped in the fluid 26 in expansion chamber 34 is 
alignable with cross-hairs 34A and 34B to provide a spirit level. When 
device 10 is level, the levelling screws 82 are adjusted to maintain the 
level condition and the mounting nuts 83 are securely fixed in place on 
the mounting screws 82. 
Device 10, once installed in the desired position on framework 16, is 
electrically connected in circuit as follows. Referring to FIGS. 2 and 10 
which show the embodiment of device 10 wherein a segmented collector ring 
40 is employed, it is seen that connector terminal 41E (which is 
electrically connected to disc 65 through the electrically conductive 
pivot assembly 13), is connected to the negative terminal of a battery B. 
The positive terminal of battery B is connectable through a single pole, 
single throw on-off switch S1 to one side of each of a plurality of relay 
coils RA, RB, RC, RD. The other side of these relay coils are electrically 
connected to the connector terminals 71A, 71B, 71C, 71D, respectively on 
device 10. Energization of a relay coil is effected by tilting of device 
10 and establishment of electrical control between disc 65 and an 
appropriate one of the segments 41A-41D. Energization of a relay coil 
effects closure of its corresponding relay contact R1A-R1D. Closure of a 
relay contact R1A-R1D effects either activation of an appropriate 
audio/visual electrical device (such as a horn or light) thereby 
indicating that tilt of a predetermined degree and in a certain direction 
has occurred. Or, if preferred, the relays could be connected to operate 
solenoid coils which direct hydraulic fluid to hydraulic levelling 
cylinders to effect levelling of the tilted machine or tilted component, 
as shown in FIG. 9. 
In the embodiment of device 10 shown in FIG. 11, wherein collector ring 40A 
is employed, disc 65 is connected through contact 41E to the negative 
terminal of battery B and the positive battery terminal is connectable 
through switch S1 to one side of a warning device such as a lamp 80. The 
other side of lamp 80 is connected through a connector terminal 71F on 
device 10 to continuous collector ring 40A. 
In operation of the embodiment shown in FIG. 11, when switch S1 is closed, 
tilting of device 10 from the position shown in FIG. 2 to the position 
shown in FIG. 9 causes a portion of the upper edge of ring 40A to make 
electrical contact with a portion of the underside of disc 65 near the 
outer edge of the latter, thereby completing an energizing circuit for 
lamp 80 which turns on to indicate to the vehicle operator that the 
vehicle or component (not shown) to which device 10 is attached has tilted 
from the vertical at least some predetermined angle in some direction, 
which angle is determined by the spacing between the contacts 65 and 40. 
With such an indication, the operator may then take such necessary action 
as may be required. As is apparent from FIG 2, if the distance between 
disc 65 and ring 40 is increased or decreased, by raising or lowering, 
respectively, the contact 65, a greater or lesser angle of tilt, 
respectively, will be required to actuate the warning light 80. Contact 65 
is raised or lowered by using a screw-driver (or similar tool) to rotate 
pin 74 in sleeve 37 thereby causing socket 68, ball 66 therein, stem 62, 
disc 65 and float 60 to be correspondingly raised or lowered. Since 
chamber 24 is completely filled and float 60 is completely immersed 
therein, raising of the float out of the liquid 26 is not possible and, 
therefore, changes in float behavior do not occur. 
In FIG. 10, when ring 40 tilts relative to disc 65, the latter engages that 
one segment 41A-41D which relates to the direction of tilt and causes 
actuating of that corresponding relay contact, indicating to the operator 
the direction of tilt or to effect operation of an appropriate levelling 
device. As will be understood, in practice, the lamps 80A-80D are so 
arranged or marked as to provide information regarding direction of tilt 
to the operator. If preferred, solenoid coils (not shown) could be used in 
place of lamps 80A-80D. 
In the embodiments shown, the warning device or devices take the form of 
lamps but it is apparent that audible warning devices, such as buzzers or 
horns, could be used in place of or in conjunction with the lamp 80 or the 
lamps 80A-80D. Furthermore, a greater or lesser number of segments could 
be provided in ring 40 as well as a corresponding number of suitable 
warning or levelling devices therefor. 
In the embodiments of the invention disclosed herein, the use of a viscous 
electrically non-conductive damping fluid affords several advantages. 
First of all, the liquid serves as an electrical insulator between the 
tiltably engageable contact members when they are in the open position. 
Second, the liquid slows the relative movement between the float and the 
housing as the device is tilted and thereby ensures that the device is not 
immediately responsive to transient conditions caused by bumps and 
potholes which would otherwise effect contact closure thereby causing 
false warnings or undesirable corrective action of the levelling device. 
The relatively large size of the float and the relatively large surface 
area of the disc exposed to the viscous liquid enhances the damping 
effect. It should also be noted that submersion of the float completely 
within the damping liquid causes a positive upwardly acting floatation 
force to be exerted and this has two benefits. First, it ensures that 
there is sound electrical contact between the relatively movable members 
in the pivot assembly at all times, without inhibiting the possiblity of 
relative pivotal motion in any direction from vertical. Second, the upward 
bouyancy force inhibits or prevents inadvertent breaking of contact within 
the pivot assembly or between the disc and collector ring which might 
otherwise result from hitting bumps or holes in rough terrain. 
As FIGS. 10 and 11 show, it is possible to include an adjustable time delay 
relay TD in the circuits controlled by the disc and collector ring. The 
advantage of such time delay is that actuation of the warning device or a 
corrective levelling device can be prevented unless the tilt condition 
exists for a predetermined length of time. In an actual embodiment of the 
invention, an adjustable time delay relay having a delay range of zero to 
ten seconds was employed and time intervals within that range were tested.