U.S. patent number 3,893,518 [Application Number 05/449,857] was granted by the patent office on 1975-07-08 for blade rotating, blade tripping and shock absorbing hydraulic cylinder for scraper-type snow plows.
This patent grant is currently assigned to Frink Sno-Plows. Invention is credited to Eugene A. Farrell.
United States Patent |
3,893,518 |
Farrell |
July 8, 1975 |
Blade rotating, blade tripping and shock absorbing hydraulic
cylinder for scraper-type snow plows
Abstract
An under the vehicle carried road scraper plow extending
substantially transversely of the vehicle has a scraper blade
carried for rotary motion from a raised position out of contact
with the road to a rotated position in contact with the road. A
pair of hydraulic cylinders pivotally mounted with respect to the
vehicle have the forward ends of their piston rods pivotally
secured to operating ears secured to the blade and extending away
from the forward surface of the blade. Each cylinder has a first
piston secured to the rearward end of its piston rod and a second
floating piston forward of the first piston, the pistons being
spaced by a compression coil spring. A hydraulic system, controlled
by a pivot valve, is arranged to provide fluid under pressure
alternatively to the front or rear of pistons in the cylinder, the
pilot valve being arranged to provide means for returning fluid to
a reservoir from the end of the cylinder not subjected to pressure.
The hydraulic line to the forward end of the cylinders is provided
with an adjustable hydraulic relief valve adjusted to a pressure
biasing the blade against the road and compressing the coil spring
of the cylinder to about half its normal length and with a pilot
operated check valve having piston means operable by pressure from
the line to the rear of the cylinders for providing drainage from
the forward ends of the cylinders when the blade is turned to
raised position.
Inventors: |
Farrell; Eugene A. (Evans
Mills, NY) |
Assignee: |
Frink Sno-Plows (Clayton,
NY)
|
Family
ID: |
23785761 |
Appl.
No.: |
05/449,857 |
Filed: |
March 11, 1974 |
Current U.S.
Class: |
172/794;
172/260.5; 267/34; 37/234; 172/264; 267/291 |
Current CPC
Class: |
E02F
3/84 (20130101); E02F 3/7645 (20130101) |
Current International
Class: |
E02F
3/84 (20060101); E02F 3/76 (20060101); E02f
003/12 () |
Field of
Search: |
;172/794,264,261,265,269,705 ;37/42R,42VL,50
;267/34,61R,63,64R,65R,122 ;91/462-466 ;280/124R,6.11X |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Eickholt; E. H.
Attorney, Agent or Firm: Bruns & Jenney
Claims
I claim:
1. In a vehicle carried snow scraper having a blade rotatable in
one direction to a raised position out of contact with the road and
rotatable in a reverse direction to a lowered position in contact
with the road, motor means for rotating the blade, comprising: a
fluid reservoir and a source of fluid under pressure, at least one
hydraulic cylinder oscillatably secured to a scraper portion fixed
to the vehicle, the cylinder having a piston therein fixed to one
end of a piston rod, a second floating piston through which the rod
is slideable, the pistons being resiliently spaced by a compression
coil spring around the rod, passages into the cylinder at the fixed
piston end and at the floating piston end, the blade having ear
means projecting therefrom, the other end of the rod being
pivotally secured to the ear means, a four way pilot valve; tubular
lines from the pilot valve connected respectively to the source of
pressure fluid, the fixed piston end passage, the reservoir, and
the floating piston end passage; the pilot valve having a first
position for connecting fluid under pressure to the fixed piston
end passage by one valve passage for raising the blade and
connecting the floating piston end passage to the reservoir by
another valve passage, the pilot valve having a second position for
connecting fluid under pressure to the floating piston end passage
by one valve passage for lowering the blade and connecting the
fixed piston end passage to the reservoir by another valve passage,
the line from the pilot valve to the floating piston end passage
including a hydraulic relief valve and a pilot operated check valve
in that order connected therein, the relief valve having a cracking
pressure chosen to turn the blade into contact with the road and to
apply sufficient pressure to the road so as to compress the
cylinder spring to substantially half its free length, a tubular
line leading from the relief valve to the reservoir for carrying
off fluid when the relief valve is cracked, the check valve having
a chamber therein and a piston in the chamber adapted to open the
check valve when the chamber is subjected to pressure, and a
tubular line from the chamber connected to the line from the pilot
valve to the fixed piston end passage for opening the check valve
when the blade is raised, whereby the blade is raised when the
pilot valve is moved to its first position and the blade is lowered
and spring loaded when the pilot valve is moved to its second
position and the cylinder acts as a shock absorbing trip for the
blade when it meets an obstruction thereby further compressing the
cylinder spring.
2. In a vehicle carried snow scraper having a portion fixed to the
vehicle and a blade hinged to the fixed portion and rotatable in
one direction to a raised position out of contact with the road and
rotatable in a reverse direction to a lowered position in contact
with the road, motor means for rotating the blade, comprising: a
fluid reservoir, a source of fluid under pressure, a pair of
transversely spaced hydraulic cylinders oscillatably secured to the
scraper fixed portion, each cylinder having a forwardly extending
piston rod whose forward end is pivotally secured to the blade, a
piston in each cylinder fixed to the rear end of the rod, a
floating piston in each cylinder through which the rod is
slideable, a compression coil spring in each cylinder around the
rod for spacing the pistons therein, a four way pilot valve;
tubular lines from the pilot valve connected, respectively, to the
source of pressure fluid, the forward and rear ends of both
cylinders, and the reservoir; the pilot valve having a first
position for connecting pressure fluid to the rear ends of both
cylinders by one valve passage for raising the blade and connecting
the forward ends of both cylinders to the reservoir by another
valve passage, the pilot valve having a second position for
connecting pressure fluid to the forward ends of both cylinders by
one valve passage for lowering the blade and connecting the ends of
both cylinders to the reservoir by another passage, the line from
the pilot valve to the forward cylinder ends including a hydraulic
relief valve and a pilot operated check valve in that order
connected therein, the relief valve being adjustable and adapted to
be adjusted to a cracking pressure chosen to turn the blade into a
loaded contact with the road sufficient to compress the cylinder
springs to substantially half of their free lengths, a tubular line
leading from the relief valve to the reservoir for carrying off
fluid when the relief valve is cracked, the check valve having a
chamber therein and a piston in the chamber adapted to open the
check valve when the chamber is subjected to pressure, and a
tubular line from the chamber connected to the line from the pilot
valve to the cylinders rear ends for opening the check valve when
the blade is raised, whereby the blade is raised when the pilot
valve is moved to its first position and the blade is lowered and
spring loaded when the pilot valve is moved to its second position
and the cylinder acts as a shock absorbing trip for the blade when
it meets an obstruction thereby further compressing the cylinder
springs.
3. The vehicle carried snow scraper defined in claim 2 wherein the
pilot valve has a third passage therethrough adapted to connect
pressure fluid to the line to the reservoir when it is turned to a
third position, the passages through the pilot valve being arranged
to close the lines to the forward and rear ends of the cylinders
when the pilot valve is turned to its third position, whereby when
the pilot valve is turned from its first position to its third
position the blade remains raised and when the pilot valve is
turned from its second position to its third position the blade
remains in contact with the road and biased downward.
Description
BACKGROUND OF THE INVENTION
This invention relates to road scraper plows for trucks and more
particularly for hydraulic means for raising and lowering the blade
thereof.
Prior art scraper plows have hydraulic cylinders for rotating the
plow blade about an axis substantially transverse the truck for
raising the blade away from the road and rotating it into contact
with the road. Such hydraulic cylinders, however, require spring
means between the plow-rotating cylinder and the blade because the
cylinder motor mechanism lacks the resiliency to allow the blade to
be tripped when it meets an obstruction in the road.
SUMMARY OF THE INVENTION
This invention contemplates providing a hydraulic cylinder and
control system therefor which has operator-controlled means for
rotating the blade from raised position to road contacting position
and back again and also provides for constant pressure of the blade
against the road surface but with resilient means within the
cylinder for allowing automatic tripping of the blade when it meets
an obstruction in the road, the blade being automatically returned
with constant pressure against the road when the obstruction is
passed.
The cylinder is provided with the usual piston fixed to the
rearward end of the piston rod and an additional floating piston
through which the piston rod is slideable, the two pistons being
biased in spaced apart relation by a heavy compression coil spring
extending around the rod between the pistons. The cylinder has two
apertures for the entrance or exit of fluid under pressure, one
forward of the pistons and the other to the rear thereof.
The hydraulic system for controlling the cylinder or cylinders, two
preferably, includes the usual pump and fluid reservoir and a
four-way three-position control or pilot valve located in the cab
of the vehicle on which the plow is mounted. For raising the blade,
the pilot valve is turned to a first position connecting fluid
under pressure from the pump to a line leading to one entrance of
each cylinder, the rearward entrance in the embodiment shown. For
lowering the blade and applying pressure of the blade on the road,
the pilot valve has a second position for connecting fluid under
pressure to another line to the opposite entrances of the
cylinders, the forward entrances.
The line to the forward entrances is provided with an adjustable
hydraulic relief valve, provided with the usual return line to the
reservoir, for providing pressure in the forward portion of the
cylinder sufficient to compress the cylinder coil spring to
substantially half its extended length thus providing a regulated
loaded pressure of the blade against the road.
A pilot operated check valve is provided in the line between the
hydraulic relief valve and the forward entrances to the cylinders
so that fluid under pressure in the forward ends of the cylinders
cannot be forced out of the cylinders so long as the pilot valve
remains in its second position.
When the blade meets an obstruction it may be tripped to a position
in which the cylinder coil spring is completely compressed or, for
smaller obstructions, less than completely compressed.
The pilot valve has a first passage for transmitting fluid under
pressure to one end or the other of the cylinders, as described
above, and also a second passage for providing return of fluid from
the end of the cylinders not under pressure. When the pilot valve
is in its second position providing pressure to the forward ends of
the cylinders, the second passage connects the line to the rearward
ends of the cylinders to a line leading to the reservoir.
The pilot operated check valve has a chamber in which a piston is
reciprocable, the check valve being rendered inoperative when
pressure is applied to the chamber. This chamber is connected by a
line connected to the pressure line to the rearward ends of the
cylinders so that when pressure is applied to the cylinder rear
ends the check valve is inoperative and fluid may move out of the
forward end of the cylinders.
The second passage through the pilot valve when it is in its first
position connects the line to the forward ends of the cylinders to
the line to the reservoir so that fluid from the cylinder front
ends can return to storage.
When the pilot valve is in its second position, the pump is
continually pumping oil under pressure to the hydraulic relief
valve which allows oil to return to the reservoir. A third passage
through the pilot valve is therefore provided and when the pilot
valve is turned to its third position this third passage connects
the pump to the line leading to the reservoir so that the pump is
no longer pumping under pressure. In this third position, the lines
to both ends of the cylinders are closed. When the pilot valve is
turned from its second position to its third position the check
valve is spring biased closed so that fluid cannot escape from the
forward ends of the cylinders and when the pilot valve is turned
from its first position to its third position fluid cannot escape
from the rear ends of the cylinders by reason of the closed line to
the cylinders and in both cases the pistons remain biased as
before.
This construction provides shock absorbing and tripping means in
the operating cylinders themselves which obviates a plurality of
spring means and their attaching means and guides in exposed
position on the plow blade. The cylinder coil springs being in the
cylinder assembly provide a more compact arrangement and a
reduction of the number of parts from constructions requiring
springs between the blades and their operating cylinders. The
hydraulic relief valve, being adjustable for different loading
pressures, provides a single adjustment for the plurality of
operating cylinders used.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a plow according to the invention
with its scraper blade extended to contact the road surface, a
supporting vehicle being fragmentarily indicated in phantom
lines;
FIG. 2 is a fragmentary rear elevational view of the plow of FIG.
1, certain parts being omitted and showing longitudinal frame
members of the supporting vehicle in section;
FIG. 3 is an end elevational view of the plow of FIG. 2 showing one
of the blade operating cylinders in side elevation;
FIG. 4 is a rear elevational view of the gimbals-type mounting
members of the cylinder shown in FIG. 3;
FIG. 5 is a diagram of the hydraulic circuit in which the blade
operating cylinders shown in FIGS. 1 and 3 are connected;
FIGS. 5a, 5b and 5c are enlarged diagrammatic views of the pilot
valve shown in FIG. 5, FIG. 5a being in blade raising position,
FIG. 5b being in blade operating position and FIG. 5c being in low
pressure pump position;
FIG. 6 is an enlarged longitudinal sectional view of the hydraulic
relief valve shown diagrammatically in FIG. 5;
FIG. 7 is an enlarged longitudinal sectional view of the pilot
valve operated check valve shown diagrammatically in FIG. 5;
FIG. 8 is a diagrammatic side elevational view of the plow blade
and one of its operating cylinders shown in full lines in operating
position, the blade being fragmentarily shown in raised position
and tripped position in broken lines; and
FIGS. 9, 10, 11 and 12 are diagrammatic, longitudinal sectional
views of an operating cylinder in blade-raised, blade-lowered but
unloaded, blade-lowered and loaded, and blade-tripped position,
respectively.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, the plow 15 of the present invention is of the
scraper blade type supported pendantly underneath a truck 16
between its front wheels 17 and rear wheels 18.
As best seen in FIGS. 2 and 3, support plates 19 are bolted to
longitudinally extending frame members 20 of the truck at 21 and a
clamping plate 22 may be included. Provision is made at 23 and 24
for suitable vertical adjustment of the plow 15.
A horizontally extending circle or turntable 25 is welded along
with suitable reinforcing ribs to the bottom edges of the plates
19. A generally transversely extending blade frame 26 is supported
by bolt 27 (FIG. 2) at the center of the turntable so as to be
rotatable with respect to the turntable for adjusting the plow at
different angles underneath the vehicle. Suitable gibs 28 at either
side of the turntable are shown in FIG. 2 secured to frame 26. As
indicated in FIG. 3, holes 29 in the gibs and cooperating notches
30 in the edge of the turntable are provided for vertically
extending locking pins, not shown, for securing the plow 15 at the
desired substantially transverse angle.
Frame 26 is substantially in the form of an angle of rugged welded
construction, having a rearwardly extending flange 31 and a pendant
vertical flange 32, as best seen in FIG. 3, extending the
transverse length of the plow. As seen in FIG. 2, reinforcing
braces 34 and 35 are secured to the flanges 31 and 32 and also to
tubular bushings or hinge tubes 36.
A scraper blade 37, including the usual curved moldboard 38 and
scraper edge 39 is hingedly connected to the frame 26 by a rod or
rods 40 seen in FIG. 3.
Moldboard 38 and reinforcing plates 41 have welded thereto tubular
bushings or hinge tubes 42. At either side of the plow a spaced
pair of operating ribs 43 are similarly welded to moldboard 38 and
other tubular bushings or hinge tubes 44 (FIG. 2).
The operating ribs 43 project away from the face of blade 37 as
ears, as shown in FIG. 3, and are provided with aligned holes 45
therethrough, each pair of ribs 43 embracing the forward end of a
piston rod 46 of a novel operating cylinder 47, the rod having a
hole 48 therethrough as shown in FIGS. 9-12. The piston rod is
pivotally connected to the ribs 43 by a pin 49, as indicated in
FIG. 8, passing through holes 45 and 48.
As best seen in FIG. 3, the reinforcing ribs 35 on frame 26 project
rearwardly of the plow and each pair is adjacent a pair of
operating ribs 43, as shown in FIG. 2. As best seen in FIG. 4 a
gimbals ring 50, adapted to securely clamp around cylinder 47, has
a gimbals shaft 51 projecting laterally on diametrically opposite
sides and received in aligned holes 52 in the rearward ends of the
ribs 35. As may be seen in FIG. 3, extension of the piston rod 46
raises the blade 37 out of contact with the road and contraction of
the rod turns the blade for contact with the road.
The vehicle mounting, frame and blade of the plow 15 are
essentially conventional as described above.
The present invention contemplates utilization of a novel form of
cylinder at 47 connected in a hydraulic circuit, shown in FIG. 5,
for not only raising and lowering the blade 37 but also, by
providing a spring within the cylinder 47, utilizing the cylinder
47 as a shock resisting and blade tripping mechanism without the
use of other spring means.
The circuit of FIG. 5 includes a pilot valve V, located in the cab
of the truck, which may be turned either to the position shown in
FIG. 5a for allowing fluid under pressure from the pump P to flow
through a pressure chamber provided with the usual check valve C
and tubular line 55 to the rear of hydraulic cylinders 47 for
turning and maintaining the blade 37 out of contact with the road
and in raised position, or to the position shown in FIG. 5b for
conducting fluid under pressure through tubular lines 56 and 57 to
the front ends of cylinders 47 for turning blade 38 into contact
with the road and for thereafter biasing the blade in contact
therewith. Lines 56 and 57 are connected through a pilot operated
check valve 58 hereinafter described.
Since the cylinder 47 (FIG. 3) rocks about an axis coaxial with the
gymbal pins 51 as it turns the blade 37, the portions of lines 55
and 57 adjacent each cylinder 47 are necessarily of flexible
tubing.
Referring to FIG. 9, each cylinder 47 has a rearward entrance-exit
59 for connection with line 55 and a forward entrance-exit 60 for
connection with line 57. The rearward end of the piston rod is
connected to a piston 61 fixed to the rod and, forward of piston
61, the rod passes through a floating piston 62 and through the
head 63 closing the forward end of the cylinder. Pistons 61 and 62
and head 63 are provided with annular grooves, as indicated, for
O-ring seals. A heavy coil compression spring 64 is interposed
between pistons 61 and 62.
Referring again to FIG. 5, it will be noted that the pilot valve V
is a four way valve and that when it is in the position shown in
FIG. 5a it has one passage 65a for conducting fluid under pressure
to the line 55 and another passage 65b for conducting fluid from
the front of cylinders 47 from line 56 to line 66 leading to
reservoir or tank T, a supply line 67 leading from the tank to pump
P.
Line 57 extends from entrances-exits 60 of the cylinders to an
entrance-exit 68 of the check chamber 69 of the pilot operated
check valve 58 shown in detail in FIG. 7. Valve 58 has an
entrance-exit 70 from beyond the spring-biased valve ball 71
connected to line 56 for receiving and returning of fluid to pilot
valve V.
Check valve 58 has another pressure fluid entrance 72 leading to a
piston chamber 73 whose piston 74 bears a rod which, when the
piston is operated, lifts ball 71 off its seat. Entrance 72 is
connected by a line 75 to line 55 so that, when line 55 is exposed
to fluid under pressure, the check valve 71 is open allowing return
of fluid to tank T.
When the pilot valve V is turned to the position shown in FIG. 5b,
it will be noted that passage 65a conducts fluid under pressure
from the pump to line 56 leading through entrance-exit 70 of valve
58 past the check valve 71 to line 57 and the forward entrance 60
of cylinders 47.
Line 56 is connected by a line 76 through a hydraulic relief valve
77, shown in detail in FIG. 6, to the line 66 leading to the tank
T. The relief valve 77 has an entrance 78 leading to a check
chamber 79 controlled by a ball valve 80 controlling the exit of
fluid from passage 78. The ball 80 is supported by a perforate
piston 81, the ball normally blocking a passage through the piston,
and the piston is biased by a spring 82 so that ball 80 is normally
biased against an upper seat. Spring 82 is adjustably anchored by a
Nylon locking device 83 so that fluid pressure in lines 56 and 57
may be adjusted to a desired cracking pressure, typically 230
p.s.i. When the pressure at entrance 78 exceeds this cracking
pressure, the ball 80 is forced away from its upper seat and fluid
is admitted through the passage in piston 81 to return to tank T
until the pressure at entrance 78 drops to the desired level.
Pressure in the forward entrances 60 of the cylinders 47 is thus
regulated to a chosen pressure. At the same time passage 65b in
pilot valve V connects line 55 to line 66 allowing fluid from the
rear of cylinders 47 to flow back to tank T.
Check valve 58 and relief valve 77 are both readily obtainable
commercial items.
Referring to FIGS. 8-12, when fluid under pressure is admitted
through an entrance 59, the fixed piston 61 is advanced to the
position shown in FIG. 9 and the floating piston, biased by spring
64, advances to the position shown expelling fluid from entrance
60. As the rod is extended blade 37 is rotated to the position
shown at 37' in FIG. 8.
When the pilot valve V is turned to the position shown in FIG. 5a,
fluid under pressure is admitted through entrance 60 to lower blade
37 to the position shown in full lines in FIG. 8. When blade 37
first contacts the ground the parts of cylinders 47 are in the
position shown in FIG. 10. Since it is desirable that the scraping
edge of blade 37 be biased against the surface of the roadway,
shown at 86 in FIG. 8, with considerable force, the setting of
spring 82 of the valve 77 is chosen so that spring 64 of the
cylinders 47 is normally partially compressed about halfway of its
completely compressed length as shown in FIG. 11, the blade being
lowered and loaded as shown at 37 in full lines in FIG. 8.
When blade 37 meets an obstruction in the roadway, it may move to a
position shown at 37" in FIG. 8, the spring 64 of the cylinders 47
being substantially fully compressed, as shown in FIG. 12.
It will now be apparent that cylinders 47 operate, not only as
operating motors for the scraper blade, but also as shock absorbing
and tripping means.
The pilot valve V has a third passage 65c therethrough and, when
the valve is moved to the third position shown in FIG. 5c, pump P
is connected directly through passage 65c to line 66 which leads to
tank T so that the pump runs freely without pressure. In the third
position, moreover, the valve entrances from lines 55 and 56 are
closed.
When valve V is turned from its first position to its third
position line 55 is closed so that fluid under pressure at the rear
ends of the cylinders 47 cannot escape through lines 55. Line 75 is
closed by the piston 74 at the pilot operated check valve 58 and
line 55 at valve V is closed. The blade will therefor remain at
position 37' of FIG. 8.
When valve V is turned from its second position to its third
position line 57 is closed by the spring operation of check valve
58. Fluid under pressure cannot escape from the forward ends of
cylinders 47 and blade 37 remains in contact with the road and
spring 64 remains partly compressed as shown in FIG. 11 and blade
37 may move to its tripped position if any obstacle is met.
* * * * *