US2645297A - Handle control for electrically driven lift trucks - Google Patents

Description

y 14,1953 o; c. G. WENNBEIG ETAL- 2,645,297

HANDLE CONTROL FOR ELECTRICALLY DRIVEN LIFT TRUCKS Filed April 29. 1949 I 5. Sheets-Sheet 1 amxs app ssca/vo OR BRA/ E a/v FIRST 51 5 0 0 r BRAKE air/= 5% I @hq Z JW HANDLE CONTROL FOR ELECTRICALLY DRivEN LIFT TRUCKS Filed April 29, 1949 July 14 1953 o. c. e. WENNBERG ETAL 3 Sheet s-Sheet 3 Patented July 14, 1953 "oFFIce HANDLE CONTROL Foa ELECTRJCAlILY v DRIVEN LIFTTRUCKS,

010v Carl Gustav Wennberg and vCurt Erik A Simon Wennberg, Karlstad, wede'n Application April 29, 1949, serial No. 90,362

In Sweden May 7, 1948 1 9 Claims. (01. 180-65),

- This invention relates to lifttrucks and more particularly to electrically driven lift trucks of the type which is provided with an operating lever or rod swingable within a certainangle, preferably in a vertical plane, in one direction or the other. Usually such lever or rod is utilized for steering the truck in different driving directions.

The main object of the invention is to provide a suitable control mechanism for lift trucks of the type referred to above. V r A furtherobject of the invention is to provide acontrol mechanism for electrically motor driven lift trucks, said control mechanism comprising a blocking contrivance determining the various control positions of a control member or handle in dependence upon the positions of the operating lever within the angle in which this lever can be adjusted.

A still further object is to provide means whereby the operating handle and the operating lever are adapted to cooperate so as to obtain a reliable control of the driving means of the lift truck: 7

An object of the invention is also to provide a control mechanism for lift trucks in which braking of the driving means of the truck, driving atdifferent speeds, and driving forward as; 7 well as backward may be effected dependent upon the position of theoperating lever or rod within various zones of the angle, within which it can be set.

A more particular object of the invention is to provide a control mechanism for lift trucks. having an operating lever being generallyswingable between two extreme positions, such as a vertical position and a horizontal position. The operating lever may be adapted to cooperate with the blocking contrivance and a contact member controlled thereby so as to take the extreme position or positions within a small angle next to the same when the contact device is set to keep the motor cut off, while a braking device is preferably being engaged to prevent the truck from rolling, the motor being then stationary. These angular ranges of the operating lever may thus be'designated as the braking zones. Adjacent these zones there may be a zone within the swingsired. It is possible to make use of all of the ing ranges of the operating lever, within which zones ofv speed for forward drive-and of all of them for backward drive. r

The invention consists in the features of construction, combinationof elements, and arrangements of parts as will be exemplified in themechanism to be hereinafter described and the scope of the application. of which willbe indicated in the following claims.

In, the. drawings in which oneflembodiment of carrying the same,. said parts. .including a cam and a braking device,

Figure 3a is a part sectional view on line 1IIa 11m in Fig. 31and illustrates a detail of the braking'device.

Figure 4 is a vrticn seamen view on a plane at right anglesto the section shown in -Fig.- 3,

the upper portion of the operating lever being removed. I v v Figures 5-9 are diagrammatic representations ofdifierent positions of the operating handle of the contact device. I v

Figurelo is a coupling diagram illustrating, in a simplified way,,,the electrical connections between the contact deviceand the driving motor.

Figure loa is an elevation of the contact member shownin Fig. 10 as seen" from the left in rigid. H

In the structure shown inthe drawings, the lift truck broadly comprises a part adapted to receive the'load,.said part having two rearw ardly directed legs I carried each by a wheel (or roller) 2, a frame iiv arranged -in..frontg of said parts, an electricaljdriving motor unit 4 comprising a carrying traction wheel5 and adapted to be turned in the frame 3 ing axis of the lift truck, and a storage battery 6 secured to the frame 3. The steering axis may be determined byv a ball bearing 4a between a rotatable steerin ring lband a stationary steeringring 40; secured .to the frame 3 as shown in Fig. 3, the steeringring 41) being carried by the wheel axle journals Ed by way of journal brackets Ad. 'In addition to the driving motor, the motor unit comprisesa transmission between the motor and the carrying traction wheel 5 and controlling means for the driving motor and the transmisabout a vertical axis,.the steersion. The latter is adapted to be thrown into service by electrical means, and is indicated in Fig. 3 as two belt transmissions b, 5c, 5d. and 50a, 50b, 580 respectively. Mounted in a bearing housing I on the front portion of the driving motor unit A is an operating rod or lever 8, in a manner such that the rod is permitted to be swung about a horizontal axis of rotation 9, preferably from a vertical extreme position (full lines in Fig. 1) into a horizontal extreme position (chain-dotted lines in Fig. l), or vice versa. The lift truck may be steered by means of the operating rod 8 in different driving directions by the turning of the driving motor unit about the vertical steerin axis and, furthermore, the operating rod is used to control the driving motor and a braking device actuating the traction wheel 5. fhis driving motor control and actuation of the brakes is effected by the swinging of the operating rod 8 into different angular positions between said extreme positions, a contact device provided in the operating rod then permitted to be adjusted into various positions of control in. dependence on the position of the operating rod within said angle. The driving motor is dis- =4 engaged and the brake engaged in the extreme positions, and next to the extreme positions are the braking zones 0, 0' within which the brake is also kept engaged. If the operating rod is swung down through the braking zone 0 from the vertical extreme position and continues downward, it passes over to an angular zone I, within which the lower speed may be thrown into service by means of the contact device, and upon a continued swinging movement the operating 1.

rod is brought into an angular zone II, where the higher speed may be thrown into service. Within this zone, the lower speed also may be thrown into service instead of the higher speed, if desired. After that follows an angular zone 1', within which only the lower speed can be thrown into service, and finally follows the braking range 0 adjacent to the horizontal extreme position, wherein braking takes place and the current to the driving motor is cut off. Thus, it is obvious that the truck cannot be started directly on the higher speed, it being always necessary first to throw the lower speed into service.

Now, to determine the various connecting facilities for the contact device in the various positions of the operating rod, the invention provides for a cam l0 having a configuration adapted for the object in view. The cam forms part of a blocking contrivance adapted to fix the various positions of the operating member of the contact device. In the construction shown, the operating member of the contact device comprises a handle it extending through the upper portion of the operating rod 8, said upper portion being formed as a hood !2 enclosing the contact device. The cam l O is rigidly arranged on or keyed to the pin or shaft 9 fixed in the bearing housing 1 and having the operating rod 8 pivotally mounted thereon. In addition to the cam 10, the blocking contrivance comprises a blocking rod l3 arranged for cooperation with the cam, said blocking rod being axially displaceable in the operating rod 8 and formed at the top with or being adapted to be actuated by a fork 14 having a shank l5, I6 on either side of a plane containing the geometrical axis of rotation A for the operating member ll of the contact device and the longitudinal axis of the operating rod, the operating member or handle H being formed within the hood I2 with a supporting surface 11 extending at right angles or sub stantially so to said plane. The fork l4 may be substituted by a head Ma, Figs. and 10a, having a blocking surface Mb at the top opposite the supporting surface ll, which forms the bottom of a recess Ila. The opposite short edges of the blocking surface Mb correspond to the points of the shanks l5, H3. The supporting surface I! is intended to cooperate with the end portions or points of the fork shanks l5, It or of the edges of the blocking surface Mb. In the example shown in Fig. 3, the blocking rod is made in two, preferably coaxial parts, that is to say an upper part [8 formed with the fork l4 and a lower part 19, to the lower end of which is secured a guiding plunger 2| fitted into a bore 2D in the lower end portion 8 of the operating rod 8. Mounted in said guiding plunger is a roller 22 cooperating with the cam disk ID. The upper part 18 of the blocking rod is displaceably fitted into a bearing block 23 on the inside of the hood l2, and is actuated by a spring 24 'arrange in said bearing block, said spring tendillg to move the fork l4 upwardly into abutting contact with the supporting surface ll. Provided in a guide 25 for the upper end of the lower portion IQ of the blocking rod is a spring 28 between an abutment 2i on said guide and a stop ring 28 on the portion 19, said spring tending to move the part l9 downwardly, so as to keep the roller 22 bearing on the periphery of the cam i6. There maybe a small play between the ends of the rod members l8, l9 fac ing each other, said play permitting of being adjusted by means of an adjusting screw 29 or the like threaded into the end of one of the rod members.

In the drawings (Fig. 3), the contact device is indicated only as taking the form of a slidin contact 3Q bearing on the peripheral portion of the operating handle I! within the hood l2, but as illustrated in Figs. 10 and 10a there may be provided the number of sliding contacts 30a, 30b, 30c and contact segments Ha, Ha, lib, llc arranged on the operating handle and other electrical contrivances required to impart different speeds to the driving motor, or adapted to engage and disengage the latter in accordance with different angular positions of the operating handle. The contact springs 30a, 30b and 300 are each connected by a lead 60 to a controller box 6| which contains relay switches for the circuits of the electromotor and their connection with the storage battery 6. Said switches and circuits are adapted to impart two different speeds to the motor, one low speed and another high speed. The controller 6! may comprise any conventional circuit, such as shown in Fig. 9 of U. S. Patent No. 2,399,605.

In the starting position illustrated, wherein the supporting surface I! is at right angles to the longitudinal direction on the blocking rod, the contact device is taken to have cut oif the current to the driving motor. At the turnin of the handle I! from this position in a clockwise direction, it is possible in dependence on the magnitude of the turning angle to throw the lower and then the higher driving speed into service for forward drive, and when the handle is turned from the starting position in a counter-clockwise direction, it is possible in a similar way to throw the lower and then the higher speed into service for backward drive, a indicated by the double arrow 3! in Fig. 3 and by the pointer 32 in Figs. 5-9. In Fig. 5, the position of the operating handle is indicated at the throwing of the lower speed into service for backward drive corresponding to'engag'ement between contact 30a and contact segment Ha, Fig. 10, and in Fig. 6 its position is indicated relative to the higher speed for backward drive corresponding to engagement between'contact 30b and segment I lb. In Fig. 7, its position is indicated for the lower speed for forward drive (3011 and Ila being engaged), and in Fi 8 the position is indicated for the higher speed for forward drive (300 and He being engaged). Fig. 9 indicates the 0 position corresponding to theposition of the parts in Figs. 3 and 10. In the starting position shown in Fig. 3, however, the blocking rod and its fork I4 prevent every turning movement of the handle H, inasmuch as the shanks of the fork are abutting against the supporting surface I! and the rod member l8'is prevented by the rod member l9 from being displaced downwardly, while the rod member I9 is kept in an upper position by means of-the cam l0, inasmuch as the roller 22 is here on a circular portion 33 of the periphery of the cam- I0. However, the cam is provided with a depression 34 of such configuration that, when the roller cooperates with difierent'parts thereof, the blocking rod can be displaced downwardly, the fork [4 being consequently unable to prevent the handle II from being turned. Those sectors of the cam within which the latter cooperates with the roller 22 for theguidance of the blocking rod into and in different positions are denoted in Fig. 3 by 0, I, II, I, and ll, in the same manner as are the angular zones for the operating rod 8 in Fig. 1. It should be noted here that the sector II, which has a curved outline concentric to the angular are 33, permits throwing of the lower as well as of the higher speed into service. When the operating rod 8 is swung forwardly from the verticalposition shown, the roller 22 rolls down into the depression 34, so that the rod member I!) is moved y the sprin 26 fora distance downwardly Within the operating rod 8. The handle I I may then be turned, but no more than permitted by the fork Hi. When the handle is turned in the one or the other direction, the supporting surface ll presses the fork downwardly, until the lowerend of the fork rod l8 isstopped by the screw 29. As long as the roller 22 is within the sector I, it only permits small displacement of the blocking rod and a corresponding small turning movement of the handle H, but when the roller reaches the sector II upon a continued downward movement of the operating rod 8, it

has permitted a further displacement of the v blocking rod, a further turning movement of the handle H being thus permitted corresponding to the lower and the higher driving speeds respectively.

The operating rod 8 is also intended to actuate the brake by means of which the traction wheel 5 of the lift truck is braked. To this end, acam 40 is formed on the lower portion of the operating rod located in the bear-inghousing ll, said cam being adapted to cooperate with a roller 4| mounted on the upper end of a double-armed lever 42. This lever is mounted on a bolt '43 on the inside of the bearing housing 1, and the lower end thereof is pivotally connected to a brake arm 45 by means ofa pin 44. The brake 45 is provided with a wedge-shaped end portion 46 extending in between a pair of rollers mounted at the free ends of a pair of brake shoes 48, the

other ends of which are carried by fixed bearing pins 49. The brake shoes are actuated by a spring 48' compressed by bolts 48""for cooperation with a'brake drum 58, which i secured on a counter-shaft between the motor 50' and the traction wheel 5. In the illustrated position of the operating rod 8, the roller 4| is outside the one end of the cam 40, the wedge-shaped end portion 46 of the brake arm being then displaced inwardly so far as not to touch the rollers 41. This is also the case, when the operating rod takes a horizontal position. If the operating rod '8 is moved forwardly from the vertical position or upwardly from the horizontal position, the cam 40 is brought into contact with the roller 4|, so that the'lever 42 is swung in a clockwise direction about the bearing bolt 43, the brake arm 45 being thus pulled to the left in Fig. 3, whilethe Wedge-shapedend portion 46 thereof forces the rollers 41 apart so as to raise the brake shoes 48 from the brake drum 50, so that the brake is disengaged. As soon as the operatin rod is moved from a driving position into the vertical or horizontal position, the brake is rendered operative.

- The arrangement described is distinguished not only by a simple construction, but also offers particular advantages in regard to reliable operation and simple manoeuvring, whereby manoeuvring faults are excluded as far as possible. For example, it is not possible to start the lift truck 'on the higher speed, it being always necessary first to switch in the lower speed. It should be noted, furthermore, that the operating handle ll of the contact device is automatically turned back into the starting position, if the operating rod 8 is swungback to the nearest extreme position from zone 11 or any of the zones I and I. This is so for the reason that the roller 22 will then be moved up toward the circular portion 33 of the cam disk to force the blocking rod with the fork [4 to exert a pressure on the supporting surface ll on the one or the other side of the turning center of the handle ll, so that a turnin moment is produced, which turns the handle back. The motor will thus always be stopped and the truck braked, when the operating rod is swung toward the extreme positions, whether the handle H is turned by the driver or not. Confusion between a higher and a lower speed is also excluded, when the lift truck is standing still.

What we claim is:

1. A control mechanism for electrically motor driven lift trucks, comprising an operating rod pivoted to be swingable to different intermediate positions between extreme positions within a certain angle, an adjustable operating handle mounted on the operating rod, a contact device operated by said handle to control the driving motor, and a blocking contrivance including a cam member for cooperation with said operating rod and handle to determine definite contact positions of said handle in dependence upon the angular positions of the operating rod relatively to the cam member and to prevent the handle to beset in other contact positions, said cam member and operating rod being relatively rotatable.

2. A control mechanism as claimed in claim 1, wherein said blocking contrivance is adapted to determine two extreme positions of the operating handle for every intermediate position of the operating rod, one of said extreme handle positions being a position for forward drive and the other a position for backward drive.

3. Acontrol mechanism for motor driven lift 'trucks, comprising a housing, a shaft keyed to.

the housing, a cam, keyed to said shaft, an-operating lever journalled on the shaft and pivoted to the housing to be swingable to various positions within a certain angle, an operating member mounted rotatably on said operating lever for adjustment to various operating positions corresponding to various motor speeds and driving directions, said member having a supporting surface, a blocking rod having one end portion formed with a blocking surface for cooperation with said supporting surface, said supporting surface having edges at opposite sides of a plane including the axis of rotation of the operating member, the other end portion being adapted to cooperate with the cam, the blocking rod being slidably mounted in the operating lever to take different positions relatively to said supporting surface as the operation lever is set to different angular positions relatively to the cam and the blocking rod engages different points of the cam.

4. A control mechanism as claimed. in claim 3, wherein the blocking rod comprises a roller for cooperation with the cam.

'5. A control mechanism as claimed in claim 3,

wherein the blocking rod comprises two coaxial spring and a member adapted to be moved by i said second mentioned spring in a direction to ward the curved surface of the cam disk, the play between the ends of said rod members facing each other being adjustable by means of a screw or the like threaded into one ofthe rod ends.

6. In lift trucks having a carrying wheel driven by an electric driving means for low speed drive and high speed drive, a control mechanism comprising an operating lever pivoted to be swingaole to various intermediate positions between .extreme positions, an adjustable operating member mounted on the operating lever, a contact device operated by said operating member to control the driving means, a blocking contrivance including an independent cam adapted to cooperate with said lever for determining definite contact positions for said contact device as switched-out positions corresponding to the extreme positions of the lever and a number of switched-in positions corresponding to the inter-' mediate positions f the lever, said cam and operating member being relatively rotatable, and the blocking contrivance being devised to permit switching-in of only a low speed within zones of intermediate positions adjacent the extreme positions of the lever and to permit switchingm of low as well as high speeds within a zone of intermediate positions between said low, speed zones,

7. In lift trucks having a carrying wheel driven by an electric driving means, a control mechanism comprising a housing and a shaft keyed to the housing, a cam keyed to the shaft, an operating lever pivoted to the shaft, a contact device for the operation of said driving means, a handle mounted adjustably on the operating lever, means in said lever cooperating with said cam to determine definite positions for said handle and contact device in dependence upon the position of the lever relatively to the cam, said cam and operating lever being relatively rotatable, a further cam secured to the lever, a brake for the drivlng means and means transmitting movement from said lever cam to the brake for disengaging and engaging the brake, the lever cam being angularly disposed relative to the cam keyed to the pin or shaft whereby the engagement and disengagement of the brake is dependent on the angular position of the operating ever.

8. A control mechanism as claimed in claim 3,

wherein the edges of the blocking surface are formed by the points of a fork at the end of the blocking rod. 9. A control mechanism as claimed in claim 6, in which the lever includes a cam on thelower end of the lever and as a part thereof and in which brake means are provided adapted to be operated by the lever through said lever cam.

Name Date Schroeder Apr. 30, 1946 Number

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