US1700382A - Elevating truck - Google Patents

Description

Jan. 29, 192.9. Y F. J. SHEPR JR ELEvAT1NG.TRUcK Filed May 3, 1926 lnvenor. FredercK JShepoTd dr.

byfma Mlm Patented Jan. 29, 1929.

uNrrn-Dg STATE-s PlA-TE'N T 0F F ICE.

FREDERICK J. SHEPARD, JR., OF .AUBURNDALIE,` MASSACHUSETTS; ASSIGNOR TO LEVIS-SHEPARD COMPANY, OF'WATERTOWN, MASSACHUSETTS, rA.CORPOIlM-k'lIOllT -OF MASSACHUSETTS.

` :sLnve'rins franck;

Application filed May 3,

rlhis invention relates to improvements in elevating trucks of the type in which the load supporting means is elevated by suitable mechanism and the descent of the load controlled by cushioning means, such as -a dash pot. ln usual truclrsof this character the load supporting means is raised by mechanism operable, preferably but -notnecessarily, y

step by .st-ep, by the'vertical swinging movements ot the tongueof the truck, thelload supporting means with the load thereupon being locked in elevated position, while the truck is transported to 'its destination, the locking mechanism then released and the descent of the load cushioned bythe dash pot. The ref transport a platform supportingfreshly' moulded cement or concrete blocks, or where used to transport other semiplastic or fragilematerials.

rlhe object of the present invention is to provide an elevatingv truck ofthe characterdescribed with mechanism for locking the load supporting means in elevated position adapted to impose a-tension upon the locking means which. will tend to unlock the same upon removal ofthe weight 01: the load sup-` porting means from the locking mechanism, thus permitting Vthe loa-d supporting means to be lowered upon the cushioning device'under the control of the operator.

ln elevating trucks ot this character'means are usually provided for releasing the elevating means after the load supporting means has been raised to, and locked in, a predetermined position.

A further object of the invention is to provide means for preventing Adisengzngement ot the elevating means or which will .compel reengagement of the Aelevating means, so that the load supporting. means will be under vthe control of the elevating means, beforeV the locking means can be released, thus necessitating transfer of the weight of the load supporting inca-ns to the cushioning means underv the control oi the elevating means.

A further object of the invention is to pro- 1926. Serial Eo'. 106,364.

vide an elevating truck. embodying the aoresaid improvements Vwhich will be of rugged construction adapted to withstand hard usage and `which will be certain in its operationfso that accident to the load, by careless dropping thereof," will be effectively eliminated.'v

Other objects and Yleatures of the invention will more fully appear from the following description and the accompanying I drawings,

and will be'particularly pointed out-inthe;

claims.

In the drawings: Fig. 1 is aview, partially in longitudinal vertical section, of the preferred 4`form of elevating truck embodying the invention;v

Fig. 2 is an enlarged detail viewV illustrating particularly'the position of the foot lever. operable to impose atension upon the locking dog;

Fig.k 3 ris a detail side elevation showing a portion of the `locking dog, a sprino' lconnected thereto and a lever operable toplace a ten sion upon the dog; and,

Fig. 4 is a detail view', partially in section, showing the inter-engaging pawl and ratchet form-ing part of the mechanism forli'tting the load supporting means, after such fur# ther elevation ot the load-supporting. means.

A preferredembodiment of the invention is disclosed. herein as applied to an elevatingY truck of the type illustrated and described in Letters Patent No. 1,445,838 granted February 2G, 1923 to the Lewis-Shepard Company assignee of Ralph M. Lovejoy. The construe tion'of the truck illustrated herein is substantially identical with that illustrated in the aforesaid Letters Patent. The frame of the truck comprises side rails 1, preferably of angle iron, connected together at the front end of'an archedv girder 2 having a central cylindrical .boss 3 in which a steering post is mounted which is provided with downwardly extending arms 4 having journals for the axle 5 of a steering wheel 6. The upper end ot the steering post has secured to it and resting upon the upper end ofthe boss 5 a split collar 7 which is clamped upon the steer- .ing post by a bolt 8. r[his collar has upwardly and forwardly extending arms 9 having bosses lO near their upper ends in which is journalled the plvoted shaft 11 of a vertical swinging. tongue. The particular form of tongueshown .in the drawings comprises a section ot pipe 12, of any desirable length,

CII

having a head 13 secured thereto and provided with suitable handles 14. The opposite end of the tubular portion of the tongue is seated in a socket in the cylindrical portion 15 of a lever which is pivoted upon the shaft 11 and is provided with an extension 16 shown in dotted lines in lig. 1 which proj ect-s over the vertical steering post.

A vertical strut 17 is pivotally connected to the extension 16 of the tongue and extends upwardly substantially in alinement with the axis of the steering post and is connected at its upper end by a swivel joint 18 tosuitable lever mechanism for raising the load supporting means. By reason of the fact that the strut 17 extends in substantial alinement with the axis of the steering post it will be obvious'that the vertical swinging move` ment of the tongue may be utilized to actuate the elevating mechanism when the tongue is in any steering position. y

The rear ends of the side bars 1 of the main frame have secured to them brackets 19 which are provided with journals for a shaft 2O upon which the rear wheels 21 of the truck are mounted.

The load supporting means illustrated herein is in the form of a platform comprising side bars 22, preferably of angle iron, a connecting rear plate 23 and front standards 24 connected by suitable transverse members 25. The front end of the load supporting means is supported by lever mechanism comprising a lever 26 having a `fiat web-like construction with journals adjacent its ends which are pivotally mounted respectively upon shafts 27 and 28, the shaft 27 being mounted in brackets 29 carried by the side frames 1 and the shaft 28 in suitable bosses in the lower portion of the standards 24. The lever member 26 has a central web 30 which extends forwardly and is pivotally connected at its front end to the lower end of an upwardly extending link 31, the upper end of which is connected by a pin 32 to a sectorshaped lever 33 which is fulcrumed upon a shaft 34 mounted in the upper ends of the standards 24. A lifting lever 35, which is pivotally mounted Vupon the same fulcrum shaft 34, extends forwardly over the axis of the steering post and is connected b the swivel 18 to the upper end of the strut 17. rlhe sector-shaped lever 33 is provided with a series of teeth 36 which are adapted to' be engaged by a dog 37 having a pivotal shaft 38.

Suitable locking mechanism is provided to co-operate with the pawl and ratchet mechanism of the lifting device so that when the lifting lever 35 is raised and lowered by the swinging movement of the tongue the dog 37 will engage successively the teeth 36 upon the sector lever 33. The deg .37, however, is provided with a notched end 39 whichwill engage the lowermost tooth 40 and prevent the dog from dropping by gravity out of enthe platform and the braclrct 19 in which the rear axle 20 is journalled. rlhe lever 26, for lifting the front end of the platform, has a rearward and downward extension 46 to the end of which a linl 47 is Connected, the opposite end of said linlr being pivotally connected in turn to a link 48 whichin turn is pivotally connected at its other end to the shaft 43 of the knee of the toggle. rlhe arrangement desirably is such that when the platform is in lowered position, as illustrated in Fig. 1, the link 48 willrest upon and extend downwardly and rearwardly from the shaft 2O so that upon forward movcn'ient of the link 27 the shaft 20 will act as a fulcrum to raise the knee of the toggle and thereby materially aid in the straightening movement of the toggle which is produced by further forward movement of the link i. y

In the operation-of the elevating mechanism, therefore, the vertical sw -Oing movement of the tongue raises the lifting lever and through the pawl 37 rais-es the sector lever 32. The movement of this l vor, acting through the linlr 31, rocks the lcv 23, 'hich supports the front end of the platfogm, about its fulcrum 27 thereby lifting the front end of the platform through the shaft connection 28 thereto. The upward movement of 'the front end of the lever 26 causes downward movement of its rearward extension 46 which draws the linlr 47 forwardly, thereby acting' to straighten the toggle which supports the rear end of the platform. Thus the platform is raised vertically without substantial movement longitudinally of the frame of the truck. l

The means for cushioning the descent of the load illustrated herein is in the form of a vertical dash pot 49 which is pivotally mounted at its lower end upon a bracket 50 carried by a transverse girder 51 which rests upon the side frames 1. The piston rod 52 of the dash pot isv pivotally connected to an arm 53 which in turn is connected to the ver-- tical link 31. The dash pot be of any suitable type which ermitsa free flow of the liquid from the upper portion of the cylinder by or through the piston to the lower portion of the cylinder during the upward movemeirtI of the piston with. means for restricting the flow of fluid from the lower portion of the cylinder by or through the piston during the Sii) descent of the load. The dash potdesirably, however, is so constructed that the liquid will exert a resistance to the descent of the platform substantially pro} ortionate to the weight of the load so that the platform will descend at substantially the same speed under different loads.

The mechanism thus described is substantially the same as that illustrated in the patenty above mentioned,

The present invention relatesr particularly to locking mechanism for retaining the load supporting means in a predetermined elevated position which may be released to permit the descent of the load, but which may be only released after the weight of the load has been imposed upon the elevating mechanism. In the preferred construction illustrated the locking means comprises a ratchet 54which may be secured to or made integral with the link 31 and which is provided with teeth complementary to the teeth 36 of the lifting sector 33. A suitable locking dog 55 cooperates with the ratchet 54 and means are provided which may be caused to impose a tension upon the dog, when the dog is in engagement with the ratchet and sustaining a part of the weight of the load supporting means, which will withdraw the dog from locking position upon removal of the weight of the load upon the dog.

In the vpreferred construction illustrated the dog 55 is secured to a rearwardly inclined arm or lever 56 which is pivotally mounted atl its lower end upon a pin 57 carried by a bracket 58 which is supported upon the cross girder 51. The arm 56 normally tends to hold the dog in a position to engage the teeth 54 of the ratchet. Desirably a helical spring 59 secured at its upper end to a pin 60 on the sector lever 33 and at its lower end to a pin 61 upon the dog, insures normal engagement of the dog and ratchet. The meansfor imposing a tension upon the dog tending to release the dog from the ratchet when it is supporting a portion of the load comprises'a helical spring 62 which may be conveniently connected to the same stud 61 upon the arm or lever 56 and which is connected at its other end to an extension 63 of a foot lever 64 which is pivotally mounted upon a shaft 65 in the ears of a bracket 66 which is .secured to the web 67 of a transverse front arch-shaped member of the main frame. The foot ylever 64 is provided with stop shoulders 63 and 69 to limit its forward and rearward movements. The lateral extension or stud 63 upon the lever`64 is so located that when the foot lever is in vertical position, illustrated in full lines in Fig. 1, and in dotted lines in Fig. 3, the spring 62 will not be under anyy substantial tension. Vhen, however, the foot lever is swung forwardly and downwardly to the position illustrated in full lines in Fig. 3 a considerable tension will be imposed upon the spring 62 which will tend to draw the dog 54 out of engagement with the ratchet. Furthermore, when the foot lever is moved to the operative position illustrated in Fig. 3 a plane, extending' through the axis of the stud 63 and the stud 61 upon which the respective ends of the spring are connected, will lie beneath the axis of the pin or shaft 65 upon which the lever 64 is fulcrumed so that the shoulder 63 will be drawn firmly against the web 67 and the spring locked in tense position.

fin the operation of the device the downward and upward swinging movements of the tongue cause the pawl 37 progressively to engage the teeth 36 of the sector 33, thus raising the sector and through the link 31 causing the lever 26 to raise the front end of the platform, while the toggle joint mechanism raises the rear end of the platform. During the lifting of the load supporting means thus step by step the dog` 55engages the successive teeth of the ratchet 54. Vhen the lowest tooth 70 of the ratchet is engaged by the dog 55 the dog 37 of the lifting lever 35 tends to swing from beneath the lowest tooth 40 of the sector 33, but is prevented therefrom as the notch 39 upon the tooth will engage the point of the` tooth 40 when the tongue is raised to its uppermost position. Furthermore the dog` 37 cannot be released from the sector 33 because further lifting of the load supporting means would find no corresponding tooth in the ratchet 54 with whichthe dog 55 might engage. The interengaging members of the lifting mechanism are prevented from disengagement until the sector 33 is raised by a downward movement of the tongue and the load lifted. The locking dog can then be removed lowered until it is sustained by the dash pot, after which an upward movement of the tongue will permit. the end of the dog to drop by gravity beneath the tooth 40 of the sector. Such upward movement of the tongue should be a quick movement. Otherwise the cushioning action of the dash pot might be suiiiciently rapid to prevent the dog 37 from being released from its engagement with the tooth 40 of the sector.

During the lifting` of the load supporting means the foot lever 64 is permitted to remain invertica-l posit-ion, shown in Fig. 1, in which position no tension is imposed upon the spring 62 so that the 'dog 55 is held in engagement with the teeth of the ratchet 54 by gravity and also by the action of the spring 59. Vihen, however, the load support-- ing means is locked in elevated position and the locking means retained in such position by the weight of the' load,y the foot lever 64 may be depressed into the position illustrated in full lines in iig. 3, thereby imposing a tension upon the spring 62 tending to withdraw the lever 56 and its dog 55 from engagcment with the teeth of the ratchet 5.4.

and the load llO i se

(ill

IVhen the load has reached' its destination the lowering of the tongue will raise the lifting level' 35 and its sector 33 sui'liciently to transfer the Weight of the load from the locking mechanism to the lifting lever 35. '.l`hereupon the spring 62 Will Withdraw the dog` 55 from engagement with the teeth of the ratchet 5st. rits the plunger 52 of the dash pot is connected to the lifting link 3l, a sli ght upward movement of the tongue will transfer the weightof the load then sustained by the lifting lever to the dash pot, and a further quick upward movement of the tongue will permit the notched end of the paWl 3'? which forms a detachable connection with the load supporting means to drop out of engagement with the tooth of the sector so that the load supporting means will be free to descend under the cushioning action of the dash pot.

It will thus be obvious that the Weight of the load supporting means is transferred from the locking device to the dash pot under the control of the elevating mechanism and during such transfer the load is under the control of the operator and may be gently leposited upon the dash pot without jolting of the load. By reason of the construction described, therefore, a gentle lowering of the platform is insured which Will substantially prevent injury to, or breakage of, objects or material resting upon the load supporting means during the lowering' of the load supporting means.

It will be understood that the embodiment of the invent-ion disclosed herein is ofA an illustrative character and is not restrictive and that various changes in form, construction and arrangement of parts may be made within the spirit and scope of the following claims.

Having thus described the invention, what is claimed as new, and desired to be secured by Letters Patent, is:

l. In an elevating truck comprising load supporting means and mechanism for elevating the load and means for cushioning the descent thereof, mechanical means for holding the load supporting means in elevated position adapted to be retained in locking position by the Weight of the load imposed thereupon, and manually operable means to impose a tension upon sai-d locking means and acting to release the locking means only when the weight of the load is transferred to the mechanism for elevating the load.

2. In an elevating truck comprising load supporting means, means for elevating the same having a detachable connection therewith, means for cushioning the 'descent of the load supporting means, mechanical locking` means for holdingI the load supporting means in elevated position adapted to be retained in locking position by the Weight of the load, manually operable means for imposing an unlocking tension upon said locking means operable to release the locking means only when the Weight of the load imposed upon the locking means is transferred to the elevating means, and means for retaining said elevatingl means in detachable connection with said load supporting means until said Weight is transferred therefrom to said cushioning means.

3. In an elevating truck comprising load supporting means, releasable means for elevating said load supporting means, locking means for holding the load supporting means in elevated position and means for cushioning the descent of the load upon release of said locking means; means operable when the load supporting` means is locked in a predetermined elevated position to impose a tension upon said locking means tending to unlock the same, whereby upon further elevation of said load supporting means the locking means will be rendered ineffective, and means for retaining said elevating means in detachableA connection with said load supporting` means until. the Weight of the load supporting means is transferred therefrom to the cushioning means after such further elevation of the load supporting means.

4l. In an elevating truck comprising load supporting means, releasable means for elevating said load supporting means, operable to raise the load supporting means, means including a dog operable to lock the'load supporting means against descent, means for cushioning the descent of said load supportin means upon release of said locking means, a spring connected to said dog, manually operable means for imposing tension upon said spring When the dog is retained in locked position by the Weight of the load supporting means, and means for retaining the elevating means in detachable connection With said load supporting means until the weight of the load supporting means is transferred to the cushioning means.

5. In an elevating` truck comprising` steen ing mechanism including a tongue mounted to swinovertically, load supporting means, releasable interengaging members connect-ing saidtongue to said load supporting means and operable by the vertical swinging movement of said tongue when the same is in any steering position to elevate the load supporting means step b-y step, locking means for holding said load supporting means in elevated position and means for cushioning the descent of the load when released by said locking means; means ,operable when the load supporting means is locked in a predetermined elevated position to impose tension upon said-locking means tending to unlock the same, whereby upon removal of the Weight of the load supporting means from the locking` means said locking means Will be rendered ineffective, and means for retaining of said inly. extending ylink connecting saidjli'fting lever to said load'supportingmeans operable .b T`vertical swinging movement of the tonOue d Q 13 2D to raise said load supporting means, adash pot connected to said link operable to cushion thedescent .ot the load, a locking dog, means on said linkco-operating with said 'dog;,a springeonnected to said dog and a manually operable lever connected to said spring operable, whensaid dog is held in locked position, to impose and maintain atension-uponsaid dog tending' to unlock the same, wherebythe weight ot the load may be readily transferred by vertical swinging movements of the tongue tothe cushioning means without jolting, the load.. ,V

7.A In an. elevating truck comprising load supporting means, steering mechanism including tongue mounted to swing vertically, a lifting vdevice comprising a leverv having avtoothedr sector, means including.a.link

connecting said lever to said load supporting means, apawl co-operating with said toothed sectork operable by the yvertical swinging movement' ot the tongue and capable oiswinging out ot engagement with said sector when the load. supporting means is supported above a predetermined height, a. dash pot connectedto said link-'operable to cushion the descentoot the load, a ratchet on .said link, a dog norinallyengaging said ratchet, a spring connected `to said dog=and a toot lever connected to said spring.` Operable when saidl dog retained in locked position bythe weigl'it ot the-load jto-impose atension upon said dog tending to withdraw it from locking position.

8. In an elevating truck comprising load supporting means, steering mechanism including a tongue mounted to swing vertically, a lifting device comprising a lever having a toothed sector, means including a link connecting said lever to said load supporting means, a pawl (2o-operating ,with saidy toothed sector operable by the vertical swinging nove-,ment of the tongue and capable ot Swinging out of engagement with said sector when the load supporting means is supported above a predetermined height, a dash pot connected to said link opeiable to cushion the descent of the load, a ratchet on said link, a dog normally engaging said ratchet, a spring connected to said dog and a toot lever connected to said spring operable, when said dog is retain-ed in locked position by the weight of the load, to impose a tension upon said dog tending to withdraw it from locking position, and means for retaining the pawl in engagement with said sector until the load supporting means has been raised above the highest eifective locking position of said dog, l

9.y In anelevating truck`comprisingload supporting means, steering mechanism .including la tongue mounted to swing vertically, a liitingdevice comprising alevervhavinga toothed sector,means including a linkconnectingsaid lever to said load supporting means, a pawl co-operating withsaid'toothed sector operable l by the ,verti cal swinging lmovement of the .tongue and capable ot swinging outkof engagement with said sector when the load supporting means is raised above a vpredetermined height, a dash pot connectedl to ysaid link operable to `cushion the descentot 'the load, a ratchet on said link, a dog normally engaging said ratchet, a spring connected to said dog, a toot lever connected to said spring operable when said dog is retained inlocked position by .the weight ot kthe load Yto impose a tension upon said dog tending to withdraw it from lockingposition, and said pawl having a notch adapted tozengage the lowest tooth of the sector when the load supporting means is locked by engagement of the dog with-the lowcrinost tooth of .the ratchet, whereby further upward movement of saidsector is necessitated to permit said .pawl to dropby gravity out ot engagement with saidsector.

lO. In an elevating truck, `comprising ja load Vsupporting' means and mechanism'for elevating the load, and means for cushioning the descent thereof, mechanical means for holding the load supporting means inelevated position adapted. :to beL retained in:.locking position by the weightot the load. imposed thereupon, and i manually operable means comprising aV lever and .a spring connecting said. lever to` the locking means, toimpose a tension uponA said lockingmeans, and acting to 4release the locking means onlywhen the weight of the load is transferred tothe mechanism. for elevating the load. i

ll. In an elevating` truck, comprising load supporting means and mechanism for ,elevating the load, andfmeans torcushioning the descent thereof, mechanical means for holding the load supportingmeans in elevated position adapted to beretained inlocking position by theweight ot the load imposed thereupon, and manually operable means to impose a tension. upony said locking means, comprising a lever and a spring connecting said lever to said locking means, means to retain said lever in tension imposing position, said manually operable means being adapted to release the locking means only when thevweight of the load is transferred to the mechanism for elevating the load.

12. In an elevating truck comprising load supporting means, means for elevating the same having a detachable'connection therewith, means for cushioning the descent of the load supporting means, mechanical locking means for holding the load supporting means in elevated position adapted to be retained in locking position by the weight of the load, manually operable means for imposing an unlocking tension upon said locking means operable to release the locking means only when the weight of the load imposed upon the locking means is transferred to the elevating means, and means comprising a rack, and a notched pawl in said elevating means for retaining said elevating means in detachable connection with said load supporting` means until the load is transferred to the cushioning` means, said pawl being thereafter released.

13. In an elevating truck, comprising load supporting means, releasable means for elevating said load supporting` means, locking means for holding the load supporting means in elevated position, and means for cushioning the descent of the load upon the release of said locking means; means operable when the load supporting means is locked in a predetermined elevated position to impose a tension upon said locking means tending to unlock the same, whereby upon further elevation of said load supporting means the locking means will be rendered ineffective, and means comprising a rack and a notched pawl in said elevating means for retaining said elevating means in detachable connection with said load supporting means until the load is transferred to the cushioning means, said pawl being thereafter released.

14C. In an elevating truck comprising load supporting means, releasable means for elevating said load supporting means, operable to raise the load supporting` means, means including a dog operable to lock the load supporting means against descent,` means for cushioning the descent of said load supporting means upon release of said locking means, a spring connected to said dog, manually operable means for imposing tension upon said spring when the dog is retained in locking position by weight of the load supporting means, and means comprising a rack and a notched pawl in said elevating means for retaining said elevating means in detachable connection with said load supporting means until the load is transferred to the cushioning means, said pawl being thereafter released.

15. In an elevating truck comprising steerrimas-se ing mechanism, including a tongue mounted to swing vertically, load supporting means, releasable and engaging members, connecting said tongue to said load supporting means, and operable by the vertical swinging movement of said tongue when the same is in any steering position to elevate the load supporting means step by step, locking meansl for holding said load supporting means in elevated position, and means for cushioning the descent of the load when released by said locking means, means operable when the load supporting means is locked in a pre-determined elevated position to impose tension upon said locking means tending to unlock the same, whereby upon removal of the weight of the load supporting means from the locking means, said locking means will be rendered ineffective, and means comprising a rack and a notched paivl in said elevating means for retaining said elevating means in detachable connection with said load supporting means until the load is transferred to the cushioning means, said pawl being thereafter released.

16. In an elevating truck, comprising load supporting means, steering mechanism, including a tongue mounted to swing vertically, a lifting device comprising a lever having a toothed sector, means including a link connecting said lever to said load supporting means, a pawl cooperating with said toothedsector operable by the vertical swinging movement of the tongue, and capable of swinging out of engagement with said sector when the load supporting means is supported above a pre-determined height, a dash-pot connected to said link operable to cushion the descent of the load, a ratchet on said link, a dog normally engaging said ratchet, a spring connected to said tongue, and a foot lever connected to said spring operable when said dog is retained in locked position by the weight of the load to impose a tension upon said dog tending to withdraw it from locking position, and means comprising a notch in said pawl for retaining said pawl in engagement with said sector until the load supporting means has been raised above the highest effective locking position of said dog.

In testimony whereof, I have signed my name to this specification.

FREDERICK J. SHEPARD, JR.

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