EP1316872A2

EP1316872A2 - Linkage unit for drive members of self-propelled vehicles such as lift trucks and the like

Info

Publication number: EP1316872A2
Application number: EP02080013A
Authority: EP
Inventors: Enzo Lodi; Elios Lodi
Original assignee: LODI LUIGI AND FIGLI Srl
Current assignee: LODI LUIGI AND FIGLI Srl
Priority date: 2001-11-30
Filing date: 2002-11-28
Publication date: 2003-06-04
Anticipated expiration: 2022-11-28
Also published as: EP1316872A3; EP1316872B1; DE60201875T2; DE60201875D1; ITRE20010115A1

Abstract

A linkage unit for drive members of self-propelled vehicles, such as manual lever or pedal actuators for the forward travel and reversing of a self-propelled vehicle, comprising two linkage members (7) to be connected to said forward travel and reversing actuators, said members being keyed onto two parallel shafts (33a, 33b) and being linked in such a manner as to rotate in phase opposition between a rest position determined by an elastic repositioning device, and two opposing operative positions determined by the activation of one or the other of said actuators, in which said linkage members and said repositioning device are located within an enclosing casing (10, 100, 101, 120) acting as a frame to be removably fixed to the structure of the self-propelled vehicle, and from which said shafts emerge with means (133) for the quick connection of said actuators, said linkage members being connected together by a connecting rod (77).

Description

This invention relates to a linkage unit for drive members of self-propelled vehicles in general, a typical but non-exclusive application of which is to lift trucks for handling goods and products.
To avoid later repetition, it should be noted that in the present context, the expression "drive members of said self-propelled vehicles in general" signifies those members placed under the control of the driver of the means to enable him to manoeuvre it. More specifically, said members can consist of actuators controllable either by a hand (usually known as levers) or by a foot (usually known as pedals).
For simplicity only the latter are referred to hereinafter.
With particular reference to said lift trucks, for their manoeuvring these are generally provided with a steering wheel, a forward travel pedal, a reversing pedal and a brake pedal.
Hereinafter for questions of clarity and simplicity specific reference will be made only to the first two pedals.
The levers of said forward travel and reversing pedals are prolonged below the tuck floor where they are linked together by a linkage unit with which transducer means, generally in the form of potentiometers, are associated.
Said transducer means are sensitive to the movements of said levers, such that on operating a pedal, for example the forward travel pedal, they feed a corresponding signal (for example of forward travel), generally amplified, to the system controlling the truck transmission unit.
Linkage units are known comprising two adjacent plates positioned below the truck floor and hinged to said floor on respective horizontal axes transverse to the longitudinal axis of the truck.
The levers of the forward travel pedal and reversing pedal are fixed to the sides of said plates, to the facing regions of these plates there being provided the movement reversing elements, which are coupled by a unilateral engagement.
Said elements generally consist of two profiled appendices positioned in mutual contact, to slide against each other during the rotations of the linkage members.
The constant mutual contact between said appendices is achieved by an automatic repositioning device, generally comprising an elastically yieldable system which constantly presses against the linkage member to return it to its rest position when the forward travel and reversing pedals are released.
Said rest position of the linkage members corresponds to the neutral central position of the forward travel and reversing pedals, in which they lie at a predetermined distance from the floor of the truck driving seat.
Starting from said neutral central position, when the truck driver operates a pedal, for example the forward travel pedal, said forward travel pedal is lowered while at the same time the reversing pedal rises by the same amount by the effect of the linkage unit.
Vice versa the forward travel pedal rises when the reversing pedal is pushed, the two returning to their neutral central position when the lastly pressed pedal is released.
Said phase opposition movement of the two forward travel and reversing pedals is provided for safety reasons, as is well known to the expert of the art.
The widespread use of such linkage units has demonstrated that they are unsatisfactory at least for the following reasons.
Firstly they are unsuitable for installation on floors of a different type, so that the installer is sometimes compelled to devise individual mounting arrangements.
In addition the two linkage members are generally heat treated, usually by quenching and tempering, with a consequent high cost increase. In addition the forward travel and reversing pedals are usually welded to the two hardened linkage members, which in addition to affecting the cost makes any service interventions, such as pedal replacement, complex.
Moreover in known linkage units the movable parts are inconveniently exposed to external agents so that extraneous materials such as dust, rubble or wash liquids can infiltrate between them, causing malfunction.
The main object of the present invention is to provide an improved linkage unit able to eliminate the aforesaid problem.
Another object of the invention is to attain said result within the context of a simple, rational, reliable, compact and economical construction which is flexible in terms of the unit installation.
Said objects are attained by a linkage unit presenting the characteristics indicated in the claims.
The characteristics and constructional merits of the invention will be apparent from the ensuing detailed description given with reference to the figures of the accompanying drawings, which illustrate a particular preferred embodiment thereof by way of non-limiting example.
Figure 1 is a side perspective view of the invention, with one of the covers of the casing omitted to better shown the parts behind it.
Figure 2 is a perspective view seen from the opposite direction to Figure 1.
Figure 3 is the section III-III of Figure 1 on an enlarged scale.
Figure 4 is the section IV-IV of Figure 3.
Figure 5 is the section V-V of Figure 4 on an enlarged scale.
Said figures, and in particular Figures 1 and 2, show a containing casing indicated overall by the reference numeral 1, which is generally of rectangular-based parallelepiped form and presents small dimensions.
Said casing 1 comprises a composite structure shaped as a rectangular frame the major sides of which are defined by the two walls indicated by 10, and the minor sides of which are defined by the two walls indicated by 100 and 101 respectively.
Said two pairs of opposing walls 10 and 100-101 are suitably joined together, for example by threaded members as indicated schematically by 99.
The longitudinal edges of the walls 10 are turned outwards, and are each provided with a series of through holes 110 for fixing two opposing covers 120.
The described casing 1 forms a containing and protection guard for the constituent elements of the linkage unit of the invention, said casing 1 also providing the means for installing the unit below the floor of a self-propelled vehicle such as a lift truck.
Said installation means are in the form either of the through holes 130 provided in the wall 101 or of the through holes 110 provided in the turned edges situated on one or the other side of the walls 10, the choice of which to use depending generally on the dimensions and/or the shape of the space available below the floor.
In the first case the longitudinal axis of the parallelepiped casing 1 is generally perpendicular to the floor, and in the second case, after possibly removing the respective cover 120, said axis is generally parallel to the floor.
In both cases, the two connection shafts 33a and 33b of the levers of the forward travel and reversing pedals are disposed horizontally, perpendicular to the travel direction of said lift truck.
Instead of said holes, threaded pins rigid with the walls 10 and 101 respectively can be provided to connect said casing to said floor. Said shafts 33a and 33b pass through respective pairs of coaxial holes provided in the walls 10 (see Figure 4), beyond which the shafts 33a and 33b are supported by bearings 2 carried by two supports 3 fixed to said walls 10.
As shown in Figure 4, one end of each shaft 33a, 33b projects beyond the respective support 3 where it presents a stem 133 to which the connection end of the lever of the forward travel or reversing pedal of the lift truck is removably connected.
In the illustrated example, said stem 133 is of generally cylindrical shape (Figures 3 to 5) on which three flats are provided for securing said lever, not shown for simplicity, which is provided with an end screw clamp.
Prismatic quick connection means different from that described can be provided.
For example the stem 133 can be square or hexagonal, the connection end of the lever correspondingly having a mating recess with relative locking screw.
Alternatively the head of said shank 133 can be provided with a square or hexagonal recessed seat, said lever being correspondingly provided with a projecting mating pin.
On the opposite end of the shaft 33a, 33b there is keyed a gear wheel 4 housed in a compartment 5 of the support 3, said compartment 5 being closed by a cover 6 (see Figure 4).
The same compartment 5 houses a usual transducer (not shown), for example in the form of a potentiometer, which is linked to said gear wheel 4 in such a manner as to sense its movements and feed to the truck transmission system corresponding forward travel or reversing command signals (usually suitably amplified).
On the central portion of each shaft 33a, 33b there is keyed a transfer member 7a, 7b consisting of a profiled metal part obtained by machine tool work.
With reference to Figure 3, said members 7a, 7b are generally shaped in cross-section as a right-angled trapezium with rounded corners.
Specifically, the inclined sides of said trapezoidal profiles face each other (see Figure 3), said members 7a, 7b presenting two opposing lugs 66 (Figures 3 to 5) in correspondence with said facing zones. Between said lugs 66 there are received the opposing ends of a connecting rod 77 which is pivoted to said members 7a, 7b by two pins indicated by 88.
The opposing ends of each pin are inserted, as a force fit, in coaxial through holes provided in said lugs 66, the central portion of the pin 88 being pivoted to the connecting rod 77 by way of a bush or bearing 55, preferably of self-lubricating type.
With said linkage members 7a, 7b there is associated an automatic repositioning device provided to elastically maintain them in their rest position shown in Figure 3, corresponding to the neutral central position of the forward travel and reversing levers of the truck.
Said repositioning device comprises two profiled plates 44 resting against those sides of the members 7a, 7b situated on one and the other side of the plane defined by the axes of the shafts 33a, 33b (Figure 3), and two leaf springs 22 which constantly force said plates 44 elastically against said members 7a, 7b.
That face of the plate 44 which contacts the member 7a or 7b is flat, whereas on the opposite face there is provided a retention recess engaged by an identically shaped portion of the respective spring 22. At its ends, the spring 22 presents two angle bends, one of which engages a rod 23 lying between the walls 10 (Figures 1 to 4), and the other is hooked through a slot 24 provided in the wall 100.
The described unit operates as follows.
When the forward travel and reversing pedals of the truck are free, the linkage unit is in its rest position shown in all the accompanying figures, in which the connecting rod 77 is perpendicular to the plane defined by the axes of the shafts 334a and 33b, and the plates 44 rest against the flat sides of the linkage members 7a, 7b (Figure 3). When one of said pedals is pushed, it causes the respective member 7a, 7b to rotate in one direction and this, by way of the connecting rod 77, causes the other member 7b, 7a to rotate in the opposite direction, with simultaneous withdrawal of the plates 44 against the elastic resistance offered by the springs 22.
Essentially, while said one pedal is being pushed towards its lowered command position, the other pedal is automatically forced towards its raised safety position.
When the previously operated pedal is released, the entire unit becomes repositioned as in Figure 3 by the effect of the springs 22. As shown in all the accompanying figures, within the casing there is also advantageously provided a profiled compartment 900 for housing the connection part of a usual brake pedal and its accessories such as an elastic repositioning system, for example a return spring, and a transducer such as a potentiometer, to feed corresponding braking signals to the brake unit of the self-propelled vehicle, in the described example a lift truck.
Said brake pedal is shown schematically only in Figure 4, in which it is indicated by the reference numeral 999. In that figure it is pivoted to the shaft 33b but there is nothing to prevent its pivoting to the shaft 33a.
That stated for the said pedal actuators is also valid for actuators of manual lever type as stated in the introduction.

Claims

A linkage unit for drive members of self-propelled vehicles, such as manual lever or pedal actuators for the forward travel and reversing of a self-propelled vehicle, comprising two linkage members (7) to be connected to said forward travel and reversing actuators, said members being keyed onto two parallel shafts (33a, 33b) and being linked in such a manner as to rotate in phase opposition between a rest position determined by an elastic repositioning device, and two opposing operative positions determined by the activation of one or the other of said actuators, characterised in that said linkage members and said repositioning device are located within an enclosing casing (10, 100, 101, 120) acting as a frame to be removably fixed to the structure of the self-propelled vehicle, and from which said shafts emerge with means (133) for the quick connection of said actuators, said linkage members being connected together by a connecting rod (77).
A unit as claimed in claim 1, characterised in that said casing presents at least two substantially flat, mutually perpendicular walls which are provided with means for its fixing to said structure, such as a series of through holes or threaded pins.
A unit as claimed in claim 1, characterised in that said casing comprises two opposing supports acting as a seat for said shafts and for usual potentiometers for measuring the rotations of these latter.
A unit as claimed in claim 1, characterised in that said linkage members have at least one wall parallel to the plane defined by said shafts.
A unit as claimed in claim 1, characterised in that said repositioning device comprises two thrust plates which are elastically clamped against said flat walls of said linkage members by two rearward leaf springs carried by the casing.
A unit as claimed in claim 1, characterised in that said quick connection means comprise a stem presenting a male or female connection element to mate with a female or male connection element provided on the respective actuator.
A unit as claimed in claim 6, characterised in that said stem is coaxial to the axis of rotation of the respective linkage member.
A unit as claimed in claim 1, characterised by comprising, within said frame-functioning casing, a compartment for housing the connection part of a usual brake pedal with relative accessories, associated with said forward travel and reversing actuators.