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Патент USA US3072221

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Jan. 8, 1963
3,072,219
J. E. OLSON
FREE LIFT CYLINDER
Original Filed March 17, 1958
5 Sheets-Sheet 1
53-'
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3
FIGJ
FlG.2
INVENTOR.
JOHN E. OLSON
BY
BUGKHORN, CHEATHAM & BLORE
ATTORNEYS‘
Jan. 8, 1963
3,072,219
J. E. OLSON
FREE LIFT CYLINDER
3 Sheets-Sheet 2
Original Filed March 17, 1958
JOHN
INVENTOR.
E. OLSON
BY
BUCKHORN,CHEATHAM& BLORE
A TTOPNEKS‘
Jan. 8, 1963
3,072,219
J. E. OLSON
FREE LIFT CYLINDER
5 Sheets-Sheet 3
Original Filed March 17, 1958
5
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BY
BUCKHORN, CHEATHAM &BLORE
A TTORNEYS
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3,072,219
Patented Jan. 8, 1963
1
2
3,072,219
ularly to FIGS 1 and 2, the truck 11, which is only dia
grammatically disclosed, has a conventional extensible
FREE LIFT CYLINDER
John E. Olson, Portland, 0reg., assignor to Hyster Com
pany, Portland, 0reg., a corporation of Nevada
Continuation of abandoned application Ser. No. 722,092,
Mar. 17, 1958. This application inn. 9, 1961, Ser. No.
81,631
7 Claims. (Cl. 187—9)
This invention relates to industrial free lift trucks and
particularly to the free lift assemblies or units of such
trucks. The present application is a continuation of my
upright structure mounted on the front thereof comprising
a pair of spaced connected outer uprights pivoted on the
truck frame and forming a ?xed outer upright structure
13, and a pair of spaced connected inner uprights forming
an inner movable upright structure 15 guided for vertical
movement in a conventional manner, not shown, by the
outer upright structure. A load carriage 17 is mounted
on the inner upright structure for movement relative
thereto in a conventional manner not necessary to dis
close. A free lift cylinder unit generally entitled 19 of
the present invention is adapted to raise the load carriage
prior application entitled “Free Lift Cylinder,” Serial No.
17 through the medium of chains 21 along the length of
722,092, ?led March 17, 1958, now abandoned; which 15 the inner upright structure 15 without extending the up
was a continuation-in-part of my prior application en
right structure, and then to move the load carriage and the
inner upright structure upwardly together.
titled “Free Lift Truck,” Serial No. 543,822, ?led October
Referring to FIGS. 1, 2 and 3, the cylinder unit 19 in
31, 1955, now Patent 2,915,144. The free lift cylinder
unit disclosed and claimed in the present application is
cludes an inner cylinder 31 constituting a plunger and
basicaly shown in my prior application, Serial No. 543,
connected at its lower end to a crossbrace 33 of the outer
822. However, in the latter application it is associated
upright structure 13. Surrounding the upper portion of
with a special upright structure, while here it is associated
the plunger 31 and slidably engaging the plunger is an
with a conventional upright structure.
intermediate cylinder 35, and surrounding the intermedi
A free lift cylinder unit is so designed that upon move
ate cylinder and slidably engaging the same is an outer
ment of one of the cylinders the load carriage of the truck 25 cylinder 3-7. The upper end of the outer cylinder 37 is
may be elevated without extending the uprights. There
closed by a cap 38 which is connected by a bracket struc
after, the uprights may be extended and the carriage ele
ture 39 to a crossbrace 40 connecting the upper ends of the
vated.
inner uprights, as best shown in FIG. 1.
The lower end of the intermediate cylinder 65 projects
Heretofore, the cylinder assemblies have been very com
plicated, requiring numerous parts, and there has been a
constant demand for simpli?cation of these units since
inherently they are expensive because of the close toler
ances that must be held and because of the extensive ma
chine work that must be performed.
It is a main object of the present invention to provide a
free lift cylinder unit which is considerably simpler than
out of the outer cylinder 37 and carries a crosshead 51
supporting a pair of sheaves 53. A larger pair of sheaves
55 is mounted on the bracket structure 39 and, thus, is in
effect carried by the inner upright structure 15.
The
chains 21 are connected at one set of ends to a flange 57
formed on the cap 38, as is best shown in FIGS. 1 and 2,
prior units and considerably less expensive.
and then are trained downwardly and passed under the
lower sheaves 53' and then upwardly over the upper
A more particular object of the invention is to provide
a free lift cylinder unit including only three cylinders,
sheaves 55 and then downwardly again past the lower
ing a load carriage and extending the uprights in the same
as will be presently explained, ?uid pressure entering the
cylinder unit will ?rst force the intermediate cylinder 35
sheaves and are anchored at 56 to the load carriage 17
wherein two of the cylinders are much shorter than the 40 as best shown in FIG. 2.
third cylinder, and yet the cylinder unit is capable of mov
The parts of the cylinder unit are so dimensioned that,
manner as is possible with more complicated cylinder
units having more cylinders, or longer cylinders.
downwardly to move the sheaves 53 downwardly relative
Various other objects of the invention will be apparent 45 to the sheaves 55. Because there are two runs of the
from the following description taken in connection with
chains that are in effect lengthened because of the sepa
the accompanying drawings wherein:
ration of the lower sheaves 53 and the upper sheaves 55,
FIG. 1 is a front View of an upright structure mounted
‘as clearly apparent from FIG. 2, the carriage 17 will be
raised at twice the speed of the crosshead.
on a lift truck ‘and incorporating a free lift cylinder unit
50
At approximately the time that the load carriage
of the present invention;
reaches the upper end of the inner upright structure 15,
FIG. 2 is a side elevational view of the upright struc
the intermediate cylinder 35 has reached its bottom-most
ture, parts being broken away for convenience in illus
limit of travel and thereafter, the outer cylinder will move
tration;
upwardly carrying the intermediate cylinder with it and
FIG. 3 is a vertical sectional view of the cylinder unit
55
also raise the inner upright structure and the load carriage
showing the same in its inoperative or rest position;
upwardly together at a one-to-one rate.
‘FIG. 4 is a horizontal section taken along line 4-4
Now, turning to the speci?c structure of the cylinder
of FIG. 3;
unit and referring particularly to FIGS. 3 and 4, the
FIG. 5 is a somewhat diagrammatic sectional view in
crosshead 51 carries a suitable packing assembly 71 slid
side elevation also showing the cylinder unit in its rest or
inoperative position;
ably engaging the exterior of the plunger 31. The plunger
carries three pads 73 at its upper end slidably engaging the
inner surface of intermediate cylinder 35. These pads
are disposed in spaced relation around the plunger and
in interdigitated relation with respect to three pads 75
sequent stage of the operation.
65
provided on the inner surface of the upper end of the
Referring to thte accompanying drawings and partic
‘FIG. 6 is a view similar to FIG. 5 but showing the cylin
der unit after it has completed its free lift movement; and
FIG. 7 is a view similar to FIG. 6 but showing a sub
3,072,219
4
intermediate cylinder 35.
These pads are for guiding
purposes as will be presently apparent.
The upper end of the intermediate cylinder 35 also car
ries a packing assembly 77 slidably engaging the inner
surface of the outer cylinder 37, and the lower end of
the outer cylinder 37 carries a guide bushing 78 and a
wiper 79 which slidably engage the outer surface of the
intermediate cylinder 35. A shoulder 80 below the pack
carriage and also the intermediate cylinder 35. During
such upward movement, the pads 75 will pass by the pads
73 and move upwardly therebeyond until the crosshead
51 engages the pads 73. The chains 21 function to hold
the intermediate cylinder 35 against any substantial turn
ing movement relative to the plunger 31 when the pads
73 and 75 are separated, so as to maintain a desired
orientation of the pads relative to one another.
When the ?uid pressure is relieved, the reverse opera
ing of the assembly 77 and a shoulder 81 surrounding the
bushing 78 serve as stops as will be presently apparent. 10 tion takes place. It is here pointed out that the ?t of
The upper end of the plunger 31 is provided with a
plug 85 having a pilot portion 87 slidably projecting into
the pilot portion 87 within the cap 38 is rather close so
that ?uid within the cap is slowly expelled therefrom.
Thus the carriage and the inner upright may be dropped
swiftly, but they are cushioned at the end of the inner up
a bore formed in the cap 38. This pilot portion 87 serves
as a guide as will be presently apparent, and has its upper
15 right travel by the the cooperation of the pilot portion 87
end tapered to readily enter the bore in the cap.
As clearly shown in FIG. 3, there is a port 91 formed
and the cap 38.
in the plunger 31 just below the plug 85 to place the in
terior of the plunger in communication with the annular
space between the outer surface of the plunger and the
inner surface of the intermediate cylinder 35.
It is here pointed out that the effective area of the in
termediate cylinder is equal to the area of the interior
of the outer cylinder minus the area of the exterior of
the plunger. The reason for this is that the intermediate
cylinder has an outer packing assembly 77 slidably en
gaging the interior of the outer cylinder and a second
packing assembly 71 engaging the exterior of the plunger
31.
The present invention provides a free lift cylinder unit
having only three cylinders, only one of which is full
length and the other two are approximately half length,
in the particular upright structure disclosed. Thus this
cylinder unit requires considerably less machining work
than prior free lift assemblies which have longer cylinders
or more cylinders. Also this cylinder weighs less than
prior free lift cylinders, and since the cylinder is disposed
forwardly of the front axle of the truck and thus tends to
tilt the truck forwardly, less counterweight at the rear of
the truck is required.
While the invention has been explained with a simple
In order that the intermediate cylinder be the ?rst
upright structure, that is, a ?xed upright structure and a
cylinder to move, its effective area multiplied by the me 30 single movable upright structure, the invention is appli
chanical advantage provided by the chains 21 must be
cable to more complicated upright structures including
third and fourth upright structures.
Having described the invention in what is considered
mediate cylinder moves downwardly the load carriage
to be the preferred embodiment thereof, it is desired that
is moved upwardly at twice the speed of the intermediate 35 it be understood that the invention is not to be limited
cylinder. However, the outer cylinder can move upward
other than by the provisions of the following claims.
ly together with the intermediate cylinder to raise the load
I claim:
carriage at a one-to-one ratio. The force urging this
1. A mast assembly comprising an extensible upright
movement is equal to the area of the plunger multiplied
structure, a load carriage movably engaging said struc
by the unit ?uid pressure. Thus to make certain that
ture, a compound cylinder unit including an inner cylin
the intermediate cylinder moves downwardly ?rst, its
der constituting a plunger, an intermediate cylinder and
effective area must be more than twice the area of the
an outer cylinder, said intermediate cylinder being shorter
plunger 31. Of course, if the mechanical advantage of
than said inner cylinder and movable downwardly upon
the chain arrangement were one-third, instead of one
the application of ?uid pressure to said cylinder unit,
half, the effective area of the intermediate cylinder would 45 means connecting said intermediate cylinder to the load
have to be more than three times the area of the plunger
carriage to elevate the load carriage without extending the
greater than the area of the plunger. That is to say, in
the form of the invention disclosed, when the inter
in order to achieve downward movement of the inter
upright structure, said outer cylinder being subsequently
mediate cylinder rather than simultaneous upward move
movable upwardly upon continued application of pressure
ment of the intermediate cylinder and the outer cylinder.
to raise the carriage and extend the upright structure, said
Referring to FIGS. 3, 4 and 5, upon the application of 60 plunger having guide portions at its upper end slidably
?uid pressure to the interior of the plunger through a
engaging the interior of said intermediate cylinder, said
port 92 in the lower end thereof, the ?uid passing through
intermediate cylinder having guide portions at its upper
the port 91 into the annular space between the plunger
end slidably engaging the exterior of said plunger, the ?rst
and the intermediate cylinder and also passing upwardly
and second mentioned guide portions being arranged to
between the pads 73 and 75, suitable space being pro 65 by-pass one another during relative movement between
vided between the pads to allow this so that this ?uid is
said intermediate cylinder and said plunger.
applied against the packing 77 as well as against the pack
2. A compound cylinder unit for a mast assembly of
ing 71. Thus, the intermediate cylinder moves down
the type having an extensible upright structure and a load
wardly raising the load carriage 17 at a two-to-one rate.
carriage movably engaging said structure, said unit com
During such downward movement, the pads 75 on the 60 prising an inner cylinder constituting a plunger, an inter
intermediate cylinder move downwardly relative to the
mediate cylinder and an outer cylinder, said intermediate
pads 73, as shown in FIG. 6, and the pads 75 function
cylinder being shorter than said inner cylinder and mov
to guide the upper end of the intermediate cylinder and
able downwardly upon the application of ?uid pressure
maintain it in a predetermined spaced relation relative
to said cylinder unit, means connecting said intermediate
to the plunger. Also during the downward movement of 65 cylinder to the load carriage to elevate the load carriage
the intermediate cylinder the pilot plug 85 maintains the
without extending the upright structure, said outer cylin
upper ends of the outer cylinder and the plunger in
der being subsequently movable upwardly upon continued
proper concentric relation relative to one another.
application of pressure to raise the carriage and extend
Just as the load carriage reaches the upper end of the
the
upright structure, said plunger having guide portions
inner upright structure, the shoulder 80 on the inter 70
at its upper end slidably engaging the interior of said
mediate cylinder engages the shoulder 81 on the outer
intermediate cylinder, said intermediate cylinder having
cylinder to limit further downward movement of the in
guide portions at its upper end slidably engaging the ex
termediate cylinder. Thereafter, the continued applica
terior of said plunger, the ?rst and second mentioned
tion of ?uid pressure causes the outer cylinder to move
upwardly to raise the inner upright structure, the load 75 guide portions being offset from one another so as to by
3,072,219
5
6
pass one another during relative movement between said
said plunger having guide portions at its upper end slid
intermediate cylinder and said plunger.
3. A compound cylinder unit including an inner cylin
ably engaging the interior of said intermediate cylinder,
said intermediate cylinder having guide portions at its
upper end slidably engaging the exterior of said plunger,
der constituting a plunger, an intermediate cylinder and
the ?rst and second mentioned guide portions being ar
an outer cylinder, said intermediate cylinder being shorter
ranged to by-pass one another during relative move
than said inner cylinder and movable downwardly upon
ment between said intermediate cylinder and said
the application of ?uid pressure to said cylinder unit,
plunger.
means for connecting said intermediate cylinder to a load
6. A compound cylinder unit for an industrial lift
carriage to elevate the load carriage without extending
the upright structure guiding said carriage, said outer cyl 10 truck, said unit including an inner cylinder constituting
a plunger, an intermediate cylinder surrounding said
inder being subsequently movable upwardly upon con
plunger at the upper portion thereof in the contracted
tinued application of pressure to raise the carriage and
position of said compound cylinder, said intermediate
extend the upright structure, said intermediate cylinder
cylinder being shorter than said plunger and being open
having packing at its lower end slidably engaging said
plunger and packing on its upper end slidably engaging 15 at its opposite ends, an outer cylinder surrounding said
said outer cylinder so that said intermediate cylinder is
ejected from said outer cylinder in plunger-like ‘fashion
with the ?uid pressure acting on the area of the annulus
intermediate cylinder and having a closed upper end
above the upper ends of the plunger and intermediate
cylinder, said intermediate cylinder having means pro
jecting below the lower end of said outer cylinder for
between the exterior of the plunger and the interior of
the outer cylinder, and guide means at the upper end of 20 supporting reeving means, said intermediate cylinder
having means at its upper end sealingly engaging the
the intermediate cylinder for establishing a guided ?t be—
interior of the outer cylinder and means at its lower end
tween the upper end of the intermediate cylinder and the
sealingly engaging the exterior of said plunger so that
plunger.
the intermediate cylinder is ejected from the outer cyl
4. A compound cylinder unit for an industrial lift
truck, said unit including an inner cylinder constituting 25 inder in plunger-like fashion with the ?uid pressure act
ing on the area of the annulus between the exterior of
a plunger, an intermediate cylinder surrounding said
the plunger and the interior of the outer cylinder, guid
plunger at the upper portion thereof in the contracted
ing means on the upper end of the intermediate cylinder
position of said compound cylinder, said intermediate
engaging the plunger to maintain a concentric relation
cylinder being shorter than said plunger and being open
between
such upper end and said plunger, said guiding
30
at its opposite ends, an outer cylinder surrounding said
means providing for the ?ow of ?uid therepast between
inter-mediate cylinder and having a closed upper end
such port means and space above said packing means,
above the upper ends of the plunger and intermediate
and means whereby ?uid under pressure may be in
cylinder, said intermediate cylinder having means pro
jected into said plunger to cause said intermediate cyl
jecting below the lower end of said outer cylinder for
inder to move downwardly and subsequently cause up
supporting reeving means, said plunger having a closed 35 ward movement of said outer cylinder, said outer cyl
upper end but having port means adjacent its upper end
inder and intermediate cylinder having inter-engaging
for the ?ow of ?uid therethrough, means at the upper end
portions to enable said outer cylinder to pull said inter
of said plunger having a sliding guided ?t with the upper
mediate cylinder upwardly during upward movement
end of said outer cylinder to hold the upper ends of said
of said outer cylinder at a time when said portions are
plunger and outer cylinder in concentric relation when
engaged.
said intermediate cylinder moves downwardly, said in
7. A mast assembly comprising an extensible upright
termediate cylinder having means at its upper end sealing
structure, a load carriage movably engaging said struc
ly engaging the interior of the outer cylinder so that the
ture, a compound ram for elevating said carriage along
intermediate cylinder is ejected from the outer cylinder
said upright structure without extension of said struc
45
in plunger-like fashion with the ?uid pressure acting on
the area of the annulus between the exterior of the
plunger and the interior of the outer cylinder, guiding
ture and then extending said structure and further ele
vating said carriage, said ram being extensible in the
direction of extension of said upright structure, said
ram comprising a plurality of telescopically-related ?uid
gaging the plunger to maintain a concentric relation be 50 operated members including an inner member constitut
tween such upper end and said plunger, said guiding
ing a plunger, an intermediate member of tubular form
means providing for the ?ow of ?uid therepast between
slidably engaging said plunger, and an outer member‘
such port means and space above said packing means, and
of tubular form slidably engaging said intermediate
means whereby ?uid under pressure may be injected into
member, said outer member being shorter than said
said plunger to cause said intermediate cylinder to move 55 plunger and having a closed end which in the contracted
downwardly and then cause said intermediate cylinder
condition of said ram is next to an end of said plunger,
said intermediate member being open at both ends and
and said outer cylinder to move upwardly.
5. A mast assembly comprising an extensible upright
in the contracted condition of said ram having one end
adjacent the mentioned end of said outer member and
structure, a load carriage movably engaging said struc
ture, a compound cylinder unit including an inner cyl 60 having its other end projecting from the other end of
inder constituting a plunger, an intermediate cylinder
said outer member, said intermediate member being
and an outer cylinder, said intermediate cylinder being
shorter than said plunger to provide for movement of
shorter than said inner cylinder and movable down
said intermediate member along said plunger a pre
determined extent without projection of said other end
wardly upon the application of ?uid pressure to said
cylinder unit, means connecting said intermediate cyl 65 of said intermediate member beyond the other end of
inder to the load carriage to elevate the load carriage
said plunger, said intermediate member having sealing
without extending the upright structure, the last-named
means at said other end thereof sealingly engaging said
means having a portion elevated by said outer cylinder
plunger and having sealing means at said one end seal
during upward movement of said outer cylinder, said 70 ingly engaging said outer member, said intermediate
outer cylinder being engageable with said upright struc
member having guide means at said one end thereof
ture during its upward movement to extend said upright
slidably engaging said plunger, reeving means intercon
structure, said outer cylinder being subsequently mov
necting said load carriage and upright structure and said
able upwardly upon continued application of pressure
other end of said intermediate member to cause eleva
to raise the carriage and extend the upright structure, 75 tion of said carriage upon movement of said inter
means on the upper end of the intermediate cylinder en
3,072,219
7
mediate member along said plunger in a direction away
from said one end of said plunger, and continued ele
vation of said carriage upon ejection of said plunger
from said intermediate and outer members, means where
by ejection of said plunger causes extension of said
upright structure, and means for supplying ?uid under
pressure to said ram to cause the above movements, the
intermediate member having a lighter load in relation
to its effective surface area than said plunger so that
said intermediate member moves ?rst.
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,505,009
Schroeder __________ __ Apr. 25, 1950
Quayle ______________ __ Aug. 8, 1950
2,518,251
2,595,959
2,670,811
Lawless ____________ __ May 6, 1952
Shaifer ______________ __ Mar. 2, 1954
62,888
France ______________ __ Feb. 16, 1955
FOREIGN PATENTS
(Addition)
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