Retractable speed bump

A retractable speed bump mounted in a street, road or roadway for controlling the speed of vehicles, which includes a generally rectangularly-shaped encasement containing upper and lower, relatively movable, wedge-shaped members slidably fitted in the encasement and configured to cooperate by means of friction-reducing means such as ball bearings in adjacent, inclined faces to selectively raise the top of the upper member above street or road level responsive to activation of a hydraulic cylinder attached to the encasement and the lower member.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a means for controlling the speed of vehicles in 
selected zones such as school and hospital zones, and more particularly, 
to a retractable speed bump which is mounted in the road, street or 
roadway and is operable to selectively raise and lower a cap member or 
block above street level by means of an internally mounted hydraulic 
cylinder to provide an impediment to the rapid movement of a vehicle over 
the roadway. The speed bump is designed to present an elevated, square or 
rectangularly-shaped obstacle which projects above the surface of the road 
or street to cause severe bumping or jolting of a vehicle when the vehicle 
tires strike the obstacle at a high rate of speed. The retractable speed 
bump of this invention may be remotely controlled, and in a preferred 
embodiment, is characterized by a generally rectangular encasement which 
is recessed in the road surface and contains upper and lower wedge-shaped 
members which slidably cooperate along inclined planes of contact with 
each other and with the floor and walls of the encasement by means of 
friction-reducing means such as ball bearings. The wedge-shaped members 
are relatively movable by operation of a hydraulic cylinder attached to 
the encasement wall and the lower wedge-shaped member to effect raising 
and lowering of the top portion of the upper member above the surface of 
the roadway. The retractable speed bump of this invention can be 
constructed of any width and length necessary to accommodate substantially 
any road, street or roadway, and may be installed as a single entity or as 
multiple assemblies, depending upon the extent of traffic control desired. 
2. DESCRIPTION OF THE PRIOR ART 
Prior art devices for controlling speed of traffic in selected zones are 
varied in design. Typical of such devices is the "Pop Up Traffic Divider" 
disclosed in U.S. Pat. No. 3,530,775 to Joseph W. Bowersox. The traffic 
divider featured in this patent includes a housing which is buried flush 
with the highway and contains a casing having a column supported on the 
casing bottom and flush with the highway at the top. An annular piston is 
disposed between the casing and the column and is moved up and down by 
differential pressure of fluid such as air. A resilient, deformable tube 
is mounted on the piston and is retracted within, and expelled from the 
casing by movement of the piston. The upper end of the column and the 
casing present a rounded body or bodies, over which the extended, 
deformable and resilient tube can be bent without injury. Another device 
which is desiged to be selectively raised and lowered in the roadway is 
the "Roadway Safety Device" disclosed in U.S. Pat. No. 3,134,184 to E. 
Neblett. This device is primarily intended to warn of one-way streets and 
avenues, and includes a hinged plate provided with warning indicia on the 
side opposite the hinge, with a spring mechanism beneath the hinge to 
effect raising and lowering of the device with respect to the road 
surface. Another device for controlling the speed of vehicular traffic is 
disclosed in U.S. Pat. No. 3,720,181, to Jack D. Elkins, and is entitled, 
"Inflatable Warning Device for Roadways." The Elkins device generally 
comprises an elongated, inflatable warning mechanism which is removably 
disposed transversely of a roadway during selected periods of time in 
order to control the speed of vehicles traversing the road. Permanently 
installed vehicular speed control devices are also known in the prior art, 
and are typified by U.S. Pat. No. 4,012,156 to William Turner. Mr. 
Turner's "Retractable Safety Speed Bump" includes an elongated half 
cylinder, hinged to and normally resting in nested configuration in a half 
cylinder-shaped receptacle disposed in the surface of the roadway, and 
adapted to hingedly swing upwardly and rearwardly against the roadway to 
present a curved protuberance on the surface of the road. 
In addition to the mechanical devices disclosed in the above described 
patents, a commonly used method of controlling the speed of vehicular 
traffic in certain areas is the use of permanently mounted blocks or 
projections cemented to the road surface, usually in staggered arrays. 
While these projections are relatively inexpensive, they are susceptible 
of being broken and displaced from their anchored position by breaking the 
bond attaching them to the roadway due to the repetitive loads sustained 
by multiple contacts with the tires of passing vehicles, and they are not 
susceptible of being removed during periods of minimum traffic or at times 
when speed control of passing vehicles is unnecessary. Such devices have 
therefore frequently become not only an eye sore, but also a nuisance 
during non-regulatory time periods. 
Accordingly, it is an object of this invention to provide a retractable 
speed bump which can be either manually or automatically and remotely 
activated to a raised and functional position above the surface of a road, 
street or roadway when its use is necessary to control the speed of 
vehicular traffic, and subsequently retracted to an elevation co-extensive 
with the roadway surface when there is no longer a necessity for 
controlling the traffic speed. 
Another object of this invention is to provide a new and improved 
retractable speed bump which is automatically or manually controlled by a 
hydraulic cylinder and includes a pair of wedge-shaped blocks slidably 
mounted in an encasement and fitted in the road or street to present a 
smooth, unimpeded extension of the street when in retracted configuration, 
and a projecting, speed-interrupting surface when in selectively extended 
configuration. 
Another object of this invention is to provide a permanently-mounted, 
retractable speed bump which is normally recessed in the surface of a 
roadway, road or street requiring vehicular traffic control, and which is 
characterized by a hydraulic cylinder, the cylinder or base of which is 
mounted in an encasement or pit, and piston of which is attached to a 
lower wedge-shaped block which interferes with an upper, upwardly 
extending block along matching, inclined faces, wherein a portion of the 
upper block is caused to project vertically above the road surface when 
the hydraulic cylinder is activated and the lower block is slidably 
disposed horizontally away from the cylinder base. 
Yet another object of this invention is to provide a new and improved 
retractable speed bump which can be mounted in recessed fashion in an 
enclosure or pit in the roadway, road or street surface, and which 
includes a bottom block having an upward standing inclined face and 
resting on the bottom of the enclosure or pit, and a top block having a 
matching, downwardly facing inclined face and carried by the bottom block, 
and at least one hydraulic cylinder mounted in one wall of the enclosure 
and having a piston cooperating with the bottom block to effect horizontal 
slidable displacement of the bottom block in the enclosure and vertical 
movement of the top block upwardly from a position normally in 
registration with the street surface to a position with a portion of the 
top block projecting above the street surface. 
A still further object of the invention is to provide a retractable speed 
bump mounted in a roadway for controlling the speed of vehicles, which 
includes a generally rectangularly-shaped encasement containing upper and 
lower, relatively movable, wedge-shaped members slidably fitted in the 
encasement and configured to cooperate by means of friction-reducing 
means, such as ball bearings, in adjacent, inclined faces to selectively 
raise the top of the upper member above street or road level responsive to 
activation of a hydraulic cylinder attached to the encasement and the 
lower member. 
SUMMARY OF THE INVENTION 
These and other objects of the invention are provided in a retractable 
speed bump characterized by a generally rectangular-shaped encasement 
carrying the base of at least one hydraulic cylinder in transverse 
relationship, a wedge-shaped bottom block slidably positioned in the 
encasement, and a wedge-shaped top block supported by the bottom block 
along inclined faces, and disposed for relative movement vertically 
responsive to activation of the hydraulic cylinder and horizontal 
displacement of the bottom block in the encasement.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIG. 1 of the drawing, the retractable speed bump of this 
invention is generally illustrated by reference numeral 1, and a pair of 
the speed bumps are shown installed in retracted configuration at the 
extreme left of FIG. 1, in street 2. A curb 3 is illustrated at the edges 
of street 2, and a shoulder 4 extends from each curb 3, as illustrated. 
Retractable speed bump 1 includes a generally rectangular-shaped 
encasement 5, having four sides and a bottom, and further includes a cap 
block 6, which slidably registers with the top opening in encasement 5 to 
facilitate the desired traffic control feature. Speed control of passing 
traffic is achieved by the projection of cap block top 12 and cap block 
shoulders 13 of cap block 6 above the surface of street 2 to engage the 
tires of motor vehicles traversing the street 2. 
Referring now to FIG. 2 of the drawing, in a preferred embodiment of the 
invention the cap block 6 is shaped to define a cap block incline 7, 
extending from a cap block base 9 upwardly, and grooved to form a cap 
block incline slot 8, as illustrated. Cap block 6 is also provided with a 
cap block vertical slot 10 opposite the cap block incline slot 8, and a 
quantity of ball bearings 11 are fitted into cap block vertical slot 10 to 
reduce friction between cap block 6 and the vertical wall of encasement 5 
adjacent cap block vertical slot 10. When retractable speed bump 1 is 
illustrated in normally retracted configuraton as illustrated in FIG. 2, 
cap block base 9 of cap block 6 rests on the top surface 27 of a stop 
block 26, secured to the corner of encasement 5 beneath cap block 6. The 
top segment of cap block incline 7 in cap block 6 rests on a wedge block 
incline 16, on wedge block 14, the latter of which is disposed beneath cap 
block 6, and is normally spaced from stop block 26. Wedge block 14 
slidably cooperates with cap block 6 by means of wedge block incline slot 
17, provided in wedge block incline 16, and adjacent and parallel to cap 
block incline slot 8, and ball bearings 11, disposed in wedge block 
incline slot 17 and cap block incline slot 8. In order to facilitate a 
friction-free horizontal movement of wedge block 14 toward stop block 26 
in encasement 5, a wedge block base slot 19 is provided in wedge block 
base 18 of wedge block 14, and additional ball bearings 11 are fitted in 
the slot, as illustrated. At least one horizontal cylinder aperture 20 is 
provided in wedge block 14, depending upon the required length of 
retractable speed bump 1 and encasement 5, as hereinafter described. A 
piston bracket 24 is mounted to the end of cylinder aperture 20, and 
carries the cylinder piston 23 of a hydraulic cylinder 21. Cylinder piston 
23 cooperates with the cylinder base 22 of hydraulic cylinder 21, and the 
cylinder base 22 is securely mounted to a vertical wall of encasement 5, 
as illustrated. Accordingly, operation of hydraulic cylinder 21 includes 
extension and retraction of cylinder piston 23 with respect to cylinder 
base 22 to effect sliding, horizontal movement of wedge block 14 on ball 
bearings 11 in encasement 5, as hereinafter described. 
Referring now to FIG. 3 of the drawing, when it is desired to extend the 
retractable speed bump 1, hydraulic cylinder 21 is activated either by 
remote control or by appropriately located valves in the area of the 
retractable speed bumps to effect an extension of cylinder piston 23 with 
respect to cylinder base 22, and a sliding movement of wedge block 14 
horizontally in the direction of the arrow. This repositioning of wedge 
block 14 effects an upward thrust on cap block 6 due to the relative 
movement of wedge block incline 16 and cap block incline 7 on ball 
bearings 11, positioned in cap block incline slot 8 and wedge block 
incline slot 17, which projects cap block 6 upwardly in the direction of 
the vertical arrows to expose cap block top 12 and cap block shoulders 13 
above the surface of street 2. Wedge block 14 continues in sliding 
displacement inside encasement 5 until wedge block face 15 contacts side 
surface 28 of stop block 26, to project cap block 6 above street 2 to the 
desired extent. When it is desired to retract cap block 6 back into 
encasement 5, the action of hydraulic cylinder 21 is reversed, and 
cylinder piston 23 retracts in cylinder base 22 to force wedge block 14 
rearwardly, and the retractable speed bump 1 assumes the configuration 
illustrated in FIG. 2. Alternatively, hydraulic cylinder 21 may be 
characterized as a single action cylinder, and when hydraulic pressure is 
released from cylinder base 22, the weight of cap block top 12 causes 
wedge block 14 to slide horizontally back to its original position as 
illustrated in FIG. 2. 
It will be appreciated by those skilled in the art that the retractable 
speed bump of this invention can be constructed of substantially any 
desired size to accommodate the width and travel area of substantially any 
roadway, road or street. Furthermore, any number of units can be utilized 
in cooperation, as illustrated in FIG. 1, to effectively control the speed 
of vehicular traffic in zones where such control is only periodically 
necessary. For example, in such areas as school zones where the speed of 
traffic must be closely controlled during school hours, the retractable 
speed bump can be extended for the desired length of time and subsequently 
retracted when children are no longer on the premises or in the area. 
It will be further appreciated by those skilled in the art that in the 
event a relatively elongated retractable speed bump 1 is required for any 
desired application, multiple cap block incline slots 8, and cooperating 
wedge block incline slots 17, cap block vertical slots 10, and wedge block 
base slots 19, each fitted with ball bearings will be necessary in 
parallel relationship, respectively, as illustrated in FIG. 4 of the 
drawing. Multiple hydraulic cylinders 21 may also be mounted in the 
encasement 5 as also illustrated in FIG. 4, to provide a stable and 
smoothly operating system over the selected span of the encasement 5. In a 
most preferred embodiment of the invention encasement 5 is fitted with a 
pair of cap block vertical slots 10, cap block incline slots 8 and 
cooperating wedge block incline slots 17, and wedge block base slots 19, 
with accompanying ball bearings 11, in substantially parallel relationship 
respectively, as illustrated in FIG. 4, to balance the retractable speed 
bump assembly 1. 
The retractable speed bump of this invention is characterized by durability 
and strength, in that the hydraulic cylinder 21 or cylinders is not 
directly exposed to impact or pressure loading from passing vehicles. The 
shock of contact between the vehicle tires and the speed bump device is 
carried by cap block 6 and wedge block 14, and hydraulic cylinder 21 is 
insulated from this shock. Furthermore, ball bearings 11 are fitted into 
the various sealed slots with minimum contact with dirt and grime in order 
to insure maximum efficiency and minimum maintenance in retraction and 
extension of the device over a long period of time. 
It will be further appreciated by those skilled in the art that alternative 
friction-reducing means, including rollers and the like can be provided in 
cap block incline 7 and wedge block incline 16, and in the vertical face 
of cap block 6 and wedge block base 18 to aid smooth relative movement of 
cap block 6 and wedge block 14 inside encasement 5. Furthermore, both cap 
block 6 and wedge block 14 may be shaped from a hard durable rock such as 
granite, or the members may be fabricated of iron or steel, as deemed 
necessary for any anticipated installation. Encasement 5 may likewise be 
shaped by excavating a pit in the street or roadway, and reinforced with a 
metal frame. However, in a preferred embodiment of the invention 
encasement 5 is shaped and fabricated of metal to facilitate smooth 
relative movement of cap block 6 and wedge block 14 therein. 
Referring again to the drawing, it will be understood that the cap block 6 
and wedge block 14 can be moved into the extended configuration by either 
manual or automatic controls attached to hydraulic cylinder 21, according 
to the knowledge of those skilled in the art. 
Accordingly, having described my invention with the particularity set forth 
above,