US1505948A

US1505948A - Jack

Info

Publication number: US1505948A
Application number: US559186A
Authority: US
Inventors: Sherwood M Chase
Original assignee: Individual
Current assignee: Individual
Priority date: 1922-05-08
Filing date: 1922-05-08
Publication date: 1924-08-26
Anticipated expiration: 1941-08-26

Description

Aug. 26, 1924. 1,505,948

S. M. CHASE JACK Original Filed May 8, 1922 9 Sheets-Sheet l j l l k NNI..

uw@ W Streuung@ S. M. CHASE Aug,

JACK I Original Filed May 1922 Shet=S`heet 2 HUIT Eumww 5,

S. M. CHASE Aug. 26, 1924.

JACK

Original Filed May 8,- 1922 9 Sheets-Sheet 4 v y/@ZW @Home Q11 3j L505948 s.M.cHAsE Jack Aug. ze, 1924.

Original Filed May 8, 1922 9 Sheets-Sheet '7 Aug. 26,- 1924. 1,505,948

s. M. CHASE JACK Original Filed May 8, 1922 9 Sheets-Sheet 8 Aug. 26, 1924. 1,505,948

s. M. CHASE JACK Original Filed May 8, 1922 9 Sheets-Sheet 9 PL/g, I0.

Patented ug. 26, 1924.

UNITED STATES SHERWOOD M. CHASE, OF COLUJNIBUS, OHIO.

JACK.

Application filed May 8, 1922, Serial No. 559,186.

To all whom it may concern.'

Be it known that I, SHERwooD M. CHASE, a citizen of the United States, residing at Columbus, in the county of Franklin and State of Ohio, have invented certain new and useful Improvements in Jacks, of which the following is a specification, reference being had therein to the accompanying drawing.

My invention relates to jacks.

It is an object of my invention to provide a jack which is adaptable to various uses and in particular in connection with lift trucks.

1t is an object of my invention to provide a jack of improved construction which shall be double acting and by one movement of the actuating member produce two movements in opposite directions.

It is a further object to provide a jack in combination with a cushioning member wherein the jack in moving in opposite directions will move portions of the cushioning means in opposite directions.

It is a further object of the invention to provide an improved form of double acting jack wherein the operator may quickly elevate the jack without excessive employment of power'.

It is a further object to provide an improved arrangement of double acting jack with a lift truck and a cushioning means wherein, when the truck the cushioning means will be expanded and the parts locked in position, and upon being unlocked the lowering of the load will be cushioned by the cushioning means.

1t is my object to provide an improved construction of jack which, operating about predetermined fulcrum points, produces simultaneous elevation and depression of parts in opposite directions and also provides as desired the looking of the parts at selected intermediate positions between the fully oollapsed and fully expanded positions of the jack.

It is a further object of the invention to provide an improved construction of jack having a novel arrangement of handle capable of being placed in any desired position and also having a novel arrangement of swivelling forward wheel.

It is a still further object of the invention to provide an improved arrangement of truck having a lifting platform so supported by novel means that it moves in a subhas been elevated,

'Renewed .Tuly 14, 1924.

stantially vertical manner whereby to economize floor space when lifting and lowering.

It is a further object to provide novel means for protecting the sides of the truck and the load from contact with walls, boxes and the like and to protect the projecting side wheels.

It is an additional obj ect to provide anovel arrangement of shock absorbing and cushioning cylinder which may be filled without disturbing the remainder of the truck, without taking it apart and without the necessity of any special apparatus. I accomplish this object by means of filling the cylinder at the top where it is convenient for the operator and may be readily sealed.

Referring to the drawings:

Fig. 1 is a plan view of a truck in its lowered position with the cushioning cylinder in section and certain of the other parts such as the main handle and swiveled lever in section;

Fig. 2 is a side elevation partially in section of the truck in the lowered position; s

Fig. 3 is a view of the truck at the forward end, enlarged, partially in section and showing the truck with its parts in partially elevated position;

Fig. 4L is a plan view vated position;

Fig. 5 is a side elevation of the truck fully elevated;

Fig. 6 is a front elevation of the truck; f

Fig. 7 is a section taken vertically along the major axis of the truck through the cushioning cylinder;

Fig. 8 is a section taken on the line 8-8 of Fig. 9 looking in the direction of the arrows;

Fig. 9 is a side elevation of the left hand side of the front of the truck;

Fig. 10 is a front elevation in detail of the means for throwing certain parts over dead center to unlock them topermit of the descent of the load.

Referring to the drawings in detail, 1 and 2 refer to the longitudinal main side frame members, to the bottom edges of which are attached laterally extending

members

3 and 4 which serve as fenders to protect the sides of the truck, the load and the side wheels. Between the forward ends of l and 2 and 3 and 4 is an arch shaped casting 5 which serves the purpose of joining the forward ends of the truck together and also forms a bearing for the front wheel 6 and its king offthe truck in elepin 7. This forward caster wheel 6 connected to the king pin 7 has mounted on the upper end of the king pin a collar 8 which is provided with a pair of upwardly extending spaced arms 9. Between the upper ends of these arms passes a transverse member 10 upon which there rocks a lever 11 which has at its upper end a socket 12 to receive the operating handle and at its other end a socket 13 tol receive the ball 14 of the link 15. The ball is retained in place by the usual plate 16 forming a ball and socket y joint between the lower end ofI 11 and the link 15. The upper end 15 also. has a ball 17 for another ball and socket joint in connection with one end of the lifting lever 18. The handle is designated generally 19.

It is thus possible for the handle to move vertically about 10 and laterally about 7. The arch shaped member 5 is provided with a pair of rearwardly extending` lugs 20-20 which, by means of bolts 21-21 are connected to rearwardly extending spaced supporting bars or plates 22 which are extended upwardly into vertical members 23 known as the cylinder guides. These upwardly ex tending members have at their uppermost ends an open slot 24 in which travels a transverse member 25. The lifting' lever 18 has its other end from that at which 15 is connected to it rotatably mounted upon 25.

It will be understood, as will be seen from Figures 2 and 3 that 18 is bifurcated having a pair of

arms

26 and 27 which carry between them a pawl 28 journaled on a transverse shaft 29 carried between the

arms

26 and 27. This pawl engages with the teeth 30 of a segment '31 which travels between the

arms

26 and 27 and is journaled as will be'seen in F ig. 8 on 25. The collars 32 formed on 31 turn on 25. 25 is integral with the top of one member of the cushioning cylinder as will be hereinafter described.

It will be also understood that 31 is likewise bifurcated so that its

arms

33 and 34 may pass downwardly on either side of the upper member .of the cushioning cylinder to a point where they are pivotally engaged with the

depressing links

35 and 36 through the

pins

37 and 38. It will be understood that these depressing links passing downwardly on either side of the cushioning cylinder, are connected at their lower ends respectively at 39 and 40 to the lower member of the cylinder and in particular to a transverse member carried thereon designated 41. The lower member of the cylinder is designated 42 and the upper member or outside shell is designated 43. There are, therefore, two cylindei's Vwhich telescope one within the other.

On this outside shell 43 is carried a rack 44. The pawl 45 is adapted to engage with this rack as 44 is elevated step by step in the manner hereinafter to be described.

43 is provided with an eye 46 to which is pivoted a link 47 of a linkage actuating an elevating toggle. This linkage is constructed as follows: 47 is pivoted at 48 to one arm of a bell crank 49 which in turn is journa-led at 50 and has its remaining arm extending at right angles to the first arm as at 51. This second arm is pivot-ally connected at 52 to one end of a short link 53 which has its other end pivotally connected at 54 to the front end of a long link 55 carrying on its rear end a` yoke men'iber 63. Carried by the yoke member 63 is a shaft 56 on which is journalled the ends of a pair of rock arms 57 projecting from a sleeve 61 revolubly mounted on a shaft 59. The shaft 59 is carried by a rear casting 60 which in turn is carried by the rear ends of the

longitudinal frame members

1 and 2. Also projecting from the slee-ve 61 are the rock arms 58. Also journaled on 56 is a member 64 proceeding forwardly for connection with the bell crank connected to the bottom member of the cushioning cylinder.

"returning to the rear end of the truck again the rock arms 58 have journaled in their outer ends a transverse member 65 upon which is mounted a web-like plate 66 having openings 67 to accommodate the ends of 63. This plate is swung from the rear top casting of the elevating platform 68 as at 69, 69 representing a transverse shaft, mounted in the platform casting or frame 68.

In order to synchronize the elevation of the rear portion of the platform with the movement of the forward portion of the platform, the connecting rod 64 is provided which is connected at 70 to a bell crank consisting of the arms 71 and '72 .pivoted at 73 on a cross member 47. The outer end of 72 is pivotally connected at 75 to 41 which is attached to the bottom member of the cushioning cylinder. The forward end of the platforn'i designated 7 6 has connected to it at 77 by a link 78 a bell crank consisting of

arms

79 and 80 journaled on a shaft 81 carried transversely between

frame members

1 and 2. 8O is also connected at 54 to 55 so that the rear and forward ends will move together as they are elevated. At- 83 is a. link designed to limit t-he movement of the platform in a forward and upward direction.` This link has one end connected to to the pin or st-ub shaft 77, and the other end carried on the rear axle 82. At 74 is a cross frame member which serves not only to connect the

side frame members

1 and 2, but also to support the rear ends of the members 22.

As the upper and lower members of the cylinder, that is 42 and 43, are moved in opposite directions the pawl 45 engages with the successive notches in the rack 44 until the elevation of member 43 and the simultaneous depression of member 42 with re spect to the frame are complete. Both of the telescope cylinders move .relatively to the frame of the truck.

In order to provide means for unlatching the pawl 45 from the rack 87 is employed. This foo-t lever 87 is carried on a rock shaft 88 to which is fixed a rock arm 89 having pivotal connection at 90 with one end of a link 91. The other end of this link 91 carries a pivot pin 92, whereon is mounted one end of a link 93. Also the pivot pin 92 is connected to a bell crank 92a which consists of the

arms

94 and 95, and is pivoted on the forward arch casting at 96. This link is in turn connected at 92 to another link 93. 95 is connected pivotally at 97 to the link 98 which in turn is connected to the pawl 45 so that as the foot pedal 87 is actuated the pawl will be with- Adrawn to disengage 1t from the rack 44 to permit the members of the cylinder to telescope together and to permit the 'load to be lowered. Connected with 93 at its upper end at 99 is a bifurcated member designated i100. This member is pivoted at 101 in the eye 102 on the outside casing 43 of the cushioning cylinder so that when the cylinder is in its expanded position as in Fig. 5, 100 will lift 94 and keep the pawl 45 in engage- -ment against the rack 44.

In Fig. 9 there will be seen the spring 103 which is connected at 104 to the pedal lever 87 and to the side frame member at 105. This spring serves to keep the pawl 45 in Alocking position with 44 and also serves to keep the parts as shown in Fig. 5 in their particular positions especially the

parts

100, 33, and similar parts.

It will be observed that when the segment 31 together with its

arms

33 and 34, and 35 and 36 are in the elevated position shown in Fig. 5, their point of connection is to the left hand of a vertical line through the axis of member 25. The purpose o-f having this occur is to get the parts over the dead center so that the pull will be directly downward and the joint will not break thus positively holding the load in its elevated position.

To secure the simultaneous uncouplingof 45 with 44 and the movement of the point of connection between 33 for instance and 35 over the dead center to permit of the descent of the lifting platform and telescoping of the cylinder, a boss or shoulder 106 is provided about midway of 100 which fits within a. cutaway portion on 35 formed by a web 107 on 35. (See Fig. 10.)

As 35 and 33 move together to the right hand, this movement will be caused upon the depression of the pedal leve-r 87 by 106 coming in contact with 107 and thereby moving 35 and 33 over the dead center permitting the parts to drop down due to the weight of the load on the platform.

44, the foot lever' The pawl 28 turns freely on 29 so that when the parts reach their position shown in Fig. 5, 28 will drop down out of engagement with 30 and upon. the descent of 30 will not interfere with the ratchet 30.

At each new elevation of the platform the pawl 28 is brought in engagement by hand with 30.

Operation: It will thus be seen that to operate this truck the first step is to depress the handle 19 after the pawl 28 has been brought in engagement with the teeth 30 and by successive steps move 31 about the axis of 25 at the same time eleva-ting 25 to nearly the top of the notch 24. In doing so it will be observed that the right hand end of 18 is likewise elevated. Simultaneously 33 is being depressed and likewise 35. Also simultaneously 44 and 45 are being brought in successive engagement step by step as the cushioning cylinder composed of the upper and lower members is being expanded. Through the interconnecting system of bell cranks and toggles and connecting rods the forward and rear ends of the platform are being elevated to lift the load and upon the complete elevation of the load 28 swings out of engagement with 30 and the' point of connection between 33 and 35 passes over the dead center so that the web 107 comes in contact with 106.

lVhen the foot lever 87 is depressed by the foot of the operator the oil in the cylinder f is restricted in its upward movement so that the descent of the truck is gradual and regulated. y

To accomplish this result the cylinder is constructed as follows (see Fig. 7).

The upper member of the cylinder is designated 43 and carries the eye 108 in which is inserted the cross member 25 on either side of the cylinder. Through this member 109 in which the eye 108 is formed is drilled a passage way 110 in which a filling tube 111 is threaded on the top of which is mounted a filling plug 112. 109 is connected to a tubular member 113 by a cross member 114. 113 engages between itself and 109 the washer 115. 113 slidingly engages with and travels within the lower member of the cylinder 42.

113 has internally threaded at the bottom thereof a plug 116. This plug carries centrally a reciprocating plunger 117 which carries a washer 118 at its upper end serving to retain a spring 119 between it and a sealing ring 120 which freely moves on 117. This sealing ring has a tapered shoulder 121 engaging with a similar tapered shoulder `on the upper side of 116. The tapers of 121 and 116 are such that they would not permit the complete engagement between the. parts so that a slight space designated 122 is left between 116 and 120. This space has opening into it a narrow passage Way 128 drilled through 116. At the end opposite to the point of communication of 128 with 122, 123 communicates with a groove 124 in a sealing Washer 125 maintained normally'against 11G by a spring 126,

one end of which rests against 125 and the other end against the head 127 of 117. This channel or groove 124 has an exit passage Way through 125 designated 128.

In 116 are drilled holes larger than 123 as at 129. The upper end of these holes communicate With the chamber 130 Within 118. The lower ends are adapted to communicate with the chamber' 131 Within 42. These openings at the lower end are also sealed upon occasion as will be explainedby the sealing ring or Washer 125.

At the lower end of 42 is threaded the plug 132 which thus joins 41 to 42.

It will be seen therefore that upon the expansion vof the parts when 113 is moved out of 42 the oil will be brought under pressure in 1130 and Will move very freely through the large holes 129 against thewvasher 125,

*pushing it away and compressing the spring 126 so that the oil ivi-ll accumulate in 131 but when the reverse takes place and the loa-d is 'placed upon the platform andthe parts. released so `that the load Will force the lmembers of the cylinder to telescope, the oil which is confined in 131 Will attempt to escape. Its only avenue -of escape Will be through the narrow holes 128, the passage Way 124 and the exit passage Way 123 into i121. against 120. This pressure of the oil will close the openings 129 by the pressure against 125 vwhich will seal those openings. The pressure Will also in 122 lift 120 against the resistancel of the spring 119 which will still further impede and retard the flow of oil so that the descent will be rgradual and regulated While the movement in t-he contrary direction can take place relatively freely. i Having thus fully described my invention, What I claim as new and desire `to secure by Letters Patent, is

1. In a jack of the class described, a load carrying member, an. expansiblel element consisting of a pair of telescoping members movable in; opposite directions, a linkage.

connecting one of the last mentioned members with one end of the load carrying member, -a second linkage connecting the other lmember of the expansible element with the remaining end o f the load carrying member, and means to expand the expansible member.

2. In a jack of the class described, a load carrying member, an expansible fluid controlled element consisting of a :pair of members movable in opposite direction, .a linkage connecting .one of lthe last mentioned members with one end of the load carrying member., .a second linkage connecting the other member of the expansible element With the remaining end of the load carrying member, and a step by step actuating mechanism operatively connected to the expansible member for expanding the same.

3. In a jack of the class described, a load carrying member, a pair of members one ex'- tending above the load carrying member and both movable vertically in opposite directions, a linkage connecting one of the said members With one end of the load carrying member, a second linkageV connecting the other member With the other end of the load carrying member, and a step by step mechanisin operatively connected to said members for operating the same.

4. In a jackof the class described, a load carrying member, i an expansible element consisting of a pair of pivotally mounted members movable in opposite direction, a linkage connecting one of the last mentioned members with one end of the load carrying member, a second linkage connecting the other member of the expansible element With the remaining end of the load carrying member, and a step by step actuating mechanism operatively connected to the expansible member for expanding the same.

5. In a device of the kind described, a load carrying platform, a dash-pot including a pair of members each free to move longitudinally With respect to the other and constituting an expansion element, .a linkage connecting one end of said platform to one member of the dash-pot, a second .linkage connecting the other end of the platform Withthe other member of the dash-pot, and means to cause said dash-pot members to move outwardly With respect to each other.

6. In a device of the kind described, a load carrying platform, a dash-pot including a pair of members each free to move lon- .gitudinally With respect to the other and constituting an expansion element, a linkage connecting one end of said platform to one member ofthe dash-pot, a second linkage connecting the other'end of the platform With the other member of the dash-pot, and a step by step actuating mechanism connected to the dash-pot members for causing the dash-pot to expand.

7. In .a device of the kind described, a load carrying platform, a dash-pot inclu-d- .ing a pair of members each free to move longitudinally With respect to the other and constituting an .expansion element, a linkage connecting one end of said platform to one member of the vdash-pot, a second linkage connecting the other end of the plat-form With vthe other member of thedash-pot, and a step by step actuating mechanism connected to the dash-pot members for causing the dash-pot to expand and including a manually operated lever.

8. In a device .of the kind described, a

load carrying platform, a dash-pot including a pair of members each free to move longitudinally with respect to the other and constituting an expansion element, a linkage connecting one end of said platform to one member of the dash-pot, a second linkage connecting the other end of the platform with the other member of the dash-pot, and a step by step actuating mechanism connected to the dash-pot members for causing the dash-pot to expand and including universally swivelled manna ly operated lever.

9. ln a device of the kind described, a load carrying platform, a dash-pot including a pair of members each free to move longitudinally with respect to 'the other and constituting an expansion element, a linkage connecting one end of said platform to one member of the dash-pot, a second linkage connecting the -otlie-r end of the platform with the other member of the dash-pot, and a. step by step actuating mechanism kconnected to the dash-pot members for causing the dash-pot to expand and including a manually opera-ted lever, said actuating mechanism further including a. toggle movable on extieme expansion of the dash-pot across its dead center line whereby to releasably hold the dash-pot expanded.

l0. ln a device of the kind described, a load carrying platform, a dash-pot including a pair o-f members each free to move longitudinally with respect to the other and constituting an expansion element, a linkage connecting one end of said platform to one member of the dash-pot, a second linkage connecting the other end of the platform with the other member o-f the dash-pot, and a step by step actuating mechanism connected yto the dash-pot members-for causing the dash-pot to expand and including a. universally swivelled manually operated lever, said actuating mechanism further including a. toggle movable on extreme expansion of the dash-pot across its dead center line whereby to releasably hold the dashpot expanded.

ll.. ln a device of the kin described, a load carrying platform, a dash-pot including a pair of members each free to move longitudinally with respect to the other and constituting an expansion element, a linkage connecting one end of said platform to one. member of the dash-pot, a second linkage connecting the other end of the platform with the other member of the dash-pot, means to cause sait dash-pot members to move outwardly with respect to each other, a ratchet carried by one of the dash-pot members, and a pawl carried by the other dash-pot member and cooperating with the ratchet to releasably hold the dash-pot expanded in intermedia-te position between its fully collapsed and fully expanded position.

12. ln a device of the kind described, a load carrying platform, a dash-pot including a pair of members each fre-e to move longitudinally with respect to the other and constituting an expansion element, a linkage connecting one end of said platform to one member of the dash-pot, ai secondlinkage connecting the other end of the platform with the other member of the dash pot,

a step by step actuating mechanism connectage connecting one end of said platform to i one member of the dash-pot, a second linkage connecting the other end of the platform with the other member ot the dash-pot, means to cause said dash-pot members to more outwardly with respect to each other, including a manually operated lever, a

ratchet carried by one of the dash-pot members, and a pawl carried by the other dashpot member and cooperating with the ratchet to releasably hold the dash-pot expanded in intermediate position between its fully "f collapsed and fully expanded position.

14. In a device of the kind described, a load carrying platform, a dash-pot including a pairof members each free to move longitudinally with respect to the other and constituting an expansion element, a linkage connecting one end of said platform to one member of the dash-pot, a second linkage connecting the other end of the platform with the other member of the ydash-pot, a step byr step actuating mechanism connected to the dash-pot members for causing the dash-pot to expand and including a universally swivelled manually operated lever, a ratchet carried by one of the dash-pot meinbers, and a pawl carried by the other dashpot member and cooperating with the ratchet to releasably hold the dash-pot expanded in intermediate position between its fully collapsed and fully expanded position. y

l5. In a device of the kind described, a load carrying platform, a dash-pot including a pair of members cach free to move longitudinally with respectl to the other and constituting an expansion element, a linkage connectingone end of said platform to one member of the dash-pot, a second linkage connecting the other end of the platform with the other member'of the dash-pot, and

a step by step actuating mechanism connected to the dash-pot members for causing the dash-pot to expand and including a manually operated lever, said actuating mechanism further including an elbow joint device movable on extreme expansion of the dashpot across its dead center line whereby to releasably hold the dash-pot expanded, a ratchet carried by one of the dash-pot members, and a pawl carried by the other dashpot member and cooperating with the ratchet to releasably hold the dash-pot expanded in intermediate position between its fully collapsed and fully expanded position.

16. In a device of the kind described, a load carrying platform, a dash-pot including a pair of members each free to move longitudinally with respect to the other and constituting an expansion element, a linkage connecting one end of said platform to one member of the dash-pot, a second linkage connecting the other end of the platform with the other member of the dash-pot, and a step by step actuating mechanism connectved to the dash-pot members for causing the dash-pot to expand and including a universally swivelled manually operated lever, said actuating mechanism further including an elbow joint device movable on extreme expansion of the dash-pot across its dead centery line whereby to releasably hold the dashp-ot expanded, a ratchet carried by `one of the dash-pot members, and a pawl carried by the other dash-pot member and cooperating with the ratchet to releasably lhold the dashpot expanded in intermediate position between its fully collapsed and fully expanded position.

17. In a device of the kind described, a load carrying platform, a dash-pot including a pair of mem-bers each free to move longitudinally with respect to the other and constituting an expansion element, a linkage connecting one end of said platform to one member of the dash-pot, a second linkage connecting the other end of the platform with the other member of the dash-pot, means including a toggle movable across its dead center line to cause said dash-pot members to move voutwardly with respect to each other, av ratch-et carried by one of the dashpot members, a pawl carried by the other dash-pot member and cooperating with the ratchet to releasably hold the dash-pot expanded in intermediate position between its fully collapsed and fully expanded position, and pedal mechanism connected with said pawl and engageable with the toggle and operable to break the toggle across its dead center line and to simultaneously release the pawl from its ratchet.

18. In a device of the kind described, a load carrying platform, a dash-pot including a pair of members each free to move longitudinally with respect to the other and constituting an expansion element, a linkage connecting one end of said platform to one member of the dash-pot, a second linkage connecting the other end of the platform with the other member lof the dash-pot, a step by step actuating mechanism including a toggle movable past its dead center line connected to the dash-pot members for causing the dash-pot to be expanded, a ratchet carried by one of the dash-pot members, and a pawl carried by the other dash-pot member and cooperating with the ratchet to releasably hold the dash-pot expanded in. intermediate position between its fully collapsed and fully expanded position, and pedal mechanism 'connected with said pawl and engageable with the toggle to break the toggle across its dead center line and to simultaneously release the pawl from its ratchet.

19. In a device of the kind described, a load carrying platform, a dash-pot including a pair of members each free to move longitudinally with respect to the other and constituting an expansion element, a linkage connecting one end of said platform to one member of the dash-pot, a second linkage connecting the other end of the platform with the other member of the dash-pot, means to cause said dash-pot members to move outwardlyywit-h respect to each other. including a toggle movable past its dead center line and a manually operated lever, a ratchet carried by one of the dash-pot members, a pawl carried by the other dash-pot member and cooperating with the ratchet to releasably hold the dash-pot expanded in f intermediate position between its fully collapsed and fully expanded position, and pedalmechanism connected with said pawl and engageable with said toggle to break the toggle across its dead center line and to simultaneously release the pawl from its ratchet.

20. In a device of the kind described, a load carrying platform, a dash-pot including a pair of members each free to move longitudinally with respect to the other and constituting an expansion element, a linkage connecting one end of said platform to one member of the vdash-pot, a second linkage connecting the other end of the platform with the other member of the dash-pot, a step by step actuating mechanism connected to the dash-pot members for causing the dash-pot to expand and including a toggle movable past its dead center line and a universally swivelled manually operated lever, a ratchet carried by one of the dashpot members, a pawl carried by the other dash-pot member and cooperating with the ratchet to releasably hold the dash-pot expanded in intermediate position between its fully collapsed and fully expanded position, and pedal mechanism connected with said pawl and engageable with the toggle to break the toggle across its dead center line and to simultaneously release the pawl from its ratchet.

2l. In a device of the kind described, a load carrying platform, a dash-pot including a pair of members each free to move longitudinally with respect to the other and constituting an expansion element, a linkage connecting one end of said platform to one member of the dash-pot, a second linkage connecting the other end of the platform with the other member of the dash-pot, a step by step actuating mechanism connected to the dash-pot members for causing the dash-pot to expand and including a manually operated lever, said actuating mechanism further including a toggle movable on extreme expansion of the dash-pot across its dead center line whereby to releasably hold the dash-pot expanded, a ratchet carried by one of the dash-pot members, a pawl carried by the other dash-pot member and cooperating with the ratchet to releasably hold the dash-pot expanded in intermediate position between its fully collapsed and fully expanded position, and pedal mechanism connected with said pawl and engageable with the toggle and operable to break the toggle across its dead center and to simultaneously release the pawl from its ratchet.

22. In a device of the kind described, a. load carrying platform, a dash-pot including a pair of members each free to move longitudinally and constituting an expansion elem-ent, a linkage connecting one end of said platform to one member of the dashpot, a second linkage connecting the other end of the platform with the other member of the dash-pot, a step by step actuating mechanism connected to the dash-pot members for causing the dash-pot to expand and including a universally swivelled manually operated lever, said actuating mechanism further including a toggle movable on extreme expansion of the dash-pot across its dead center line whereby to releasably hold the dash-pot expanded, a ratchet carried by one of the dash-pot members, a pawl carried by the other dash-pot member and cooperating witli the ratchet to releasably hold the dash-pot expanded in intermediate position between its fully collapsed and fully expanded position, and pedal mechanism connected with said pawl and engageable with the toggle and operable to break th-e toggle across its dead center and to simultaneously release the pawl from its ratchet.

In testimony whereof I allix my signaturc.

SHERVVOOD M. CHASE.