Control assembly for operating an agricultural tractor

A control assembly for operating an agricultural tractor has control members (21, 22, 23, 25, 26) grouped onto a control unit (20) carried by an arm rest (1) intended to be associated to the driver's seat of the tractor. The arm rest (1) comprises a body (2) connected to a support (3) in a swingable way with adjustable inclination, as well as in a longitudinally slidable and adjustable way, and also in a rotatable way with adjustable angular position.

BACKGROUND OF THE INVENTION 
The present invention is related to control assemblies for operating 
agricultural tractors provided with a power-shift electronically 
controlled transmission with a reversing gear and associated first control 
members for the gear ratio shifting and second control members for 
selecting forward and reverse speed, as well as with an electronic control 
device for the engine rotation speed with associated third control 
members. 
Traditionally the above control members for operating an agricultural 
tractor are arranged in different areas within the driver's cab or, 
according to more recent solutions, they are grouped in a control handle, 
which may possibly perform additional functions. In both cases operation 
of the control members by the driver can be sometimes uncomfortable and 
inconvenient. 
It is known, in the field of bulldozers and earthworking vehicles, to have 
a control console arranged on one side of the vehicle operator's seat. For 
instance, patent U.S. Pat. No. 4,646,869 discloses a console with 
projecting control levers and patent U.S. Pat. No. 5,244,066 shows a 
control console with control levers and a rotary knob extending from the 
front end of an operator's seat handrest. These arrangements employ 
mechanical linkages housed within the console, thus involving problems of 
encumbrance and a bulky construction. Moreover, operation thereof may be 
uncomfortable and fatiguing. 
Similar arrangements, specifically applied to tractors, are also disclosed 
in patents U.S. Pat. No. 4,055,230 and U.S. Pat. No. 5,086,869 as well, in 
connection with a fork lift truck, in FR-A-2.388.692. 
Also known are, in the field of omnibus and cars and even aircrafts, switch 
control units for operating auxiliary electrical equipment, which are 
carried by a vehicle seat armrest, as in the case of European patent 
application EP-A-0537718 and patent U.S. Pat. No. 4,416,488. 
SUMMARY OF THE INVENTION 
The object of the present invention is to provide a control assembly for 
operating an agricultural tractor of the above-referenced type, arranged 
on an armrest intended to be associated to the driver's seat of the 
tractor, which is simple, functional and of reduced encumbrance and which 
can be more conveniently, readily and easily actuated by the driver. 
According to the invention, this object is achieved essentially by virtue 
of the fact that said first, second and third control members of the 
control assembly are constituted by respective keys grouped on an 
electrical control unit fitted within a front depression of the arm rest 
body, substantially flush with said body. 
The arm rest body conveniently further comprises a substantially vertical 
support adapted to be secured to the driver's seat of the tractor, and the 
arm rest body is swingably connected to said support around a 
substantially horizontal axis oriented transversally of said body. In this 
case adjustment means are provided for adjusting the inclination of the 
body relative to the support of the arm rest. 
Furthermore, the arm rest body may advantageously be connected to the 
support in a longitudinally displaceable way, and adjustment means are 
provided for adjusting the longitudinal position of the body relative to 
the support. 
The arm rest body may further be rotatably connected to said support around 
a substantially vertical axis, and in this case adjustment means are 
provided for adjusting the angular position of the body relative to said 
substantially vertical axis. 
In case the agricultural tractor is further provided with an electronically 
controlled fine adjustment device of the engine rotation speed and 
associated manual control member, said manual control member is 
conveniently constituted by a roller rotatably carried by said control 
unit on one side of the arm rest. 
In case the tractor is provided with a three-point hitch having an 
electronically controlled power lift with associated fourth control 
members, these fourth control members are also conveniently constituted by 
respective keys arranged on said control unit carried by the arm rest. 
According to another feature of the invention, the arm rest is further 
provided with a consent push button which is manually operable for 
activating and deactivating said control unit.

DETAILED DESCRIPTION OF THE INVENTION 
Referring initially to FIGS. 1-6, reference numeral 1 generally designates 
an arm rest which is intended to be applied on one side of the seating 
portion of a driver's seat of an agricultural tractor, not shown since of 
a generally conventional type. The arm rest 1 comprises a substantially 
horizontal elongated body 2 carried on top of a shaped plate 3 provided 
for securing the arm rest 1 to the seat structure. 
The body 2 comprises an inner rigid framework 4 incorporated within a 
member 5 of foamed plastic material or the like, having a rear portion 6 
with a substantially upside-down U shape, and a tapered front portion 7 
formed superiorly with a depression 8. 
Referring in detail to FIGS. 4 and 5, the rear portion 6 of the body 2 of 
the arm rest 1 is interiorly provided with a longitudinal sliding guide 9 
which is fixed to the framework 4 by means of screws 10 and is slidably 
engaged along a complementary stationary guide 11, fixed by means of 
screws 12 to a bracket 13 projecting below the body 2. 
The bracket 13 is connected at a lower end thereof to the upper portion of 
the plate 3, through a friction articulated joint 14 by means of which the 
body 2 is swingable relative to the tractor seat between a substantially 
vertical raised position, and a lowered position depicted in the drawings. 
The configuration of the body 2 in the lowered position is adjustable on 
opposite sides with respect to a perfectly horizontal position (shown in 
the figures) for a certain angular amplitude around the horizontal 
transverse axis of the articulated joint 14, to the aim of adjusting the 
inclination of the body 2 of the arm rest 1 to the user's need. For such 
an adjustment a rotatable threaded stop member 15 is provided for, which 
is carried by the plate 3 and is frontally abutting at its inner end 
against the bracket 13. By screwing or, respectively, unscrewing the stop 
member 15 relative to the plate 3, a corresponding variation of the 
angular position of the bracket 13 is achieved in the lowered position of 
the body 2 of the arm rest 1, with a more or less inclination of this body 
2 upwardly or, respectively, downwardly. 
By means of the two longitudinal guides 9 and 11, the longitudinal position 
of the body 2 of the arm rest 1 can be adjusted relative to the plate 3, 
as a function of the user's need. To such effect a swinging lever 16 is 
provided which is placed beneath the rear portion 6 of the body 2 and has 
an anchoring part 17 rotatably connected on one side to the guide 9. On 
the other side, the anchoring part 17 is formed with a retaining tooth 18 
which is adapted to be selectively engaged into one of a number of 
equally-spaced apart notches or slits 19 formed in the lower portion of 
the stationary guide 11. A traction helical spring 16a draws the lever 16 
towards the engaged position, so as to prevent sliding of the body 2 
relative to the plate 3. 
For the longitudinal adjustment of the body 2 relative to the plate 3 it is 
sufficient to manually move upwardly the lever 16, against the action of 
the spring 16a, so as to disengage the retaining tooth 18 from the 
corresponding notch 19, and then to displace the body 2 by sliding the 
guide 9 along the guide 11 until the desired position is reached. Locking 
in this position is automatically performed by releasing the lever 16 
which is thus brought by the spring 16a to the lowered position, so as to 
have the retaining tooth 18 engaged within the notch 19 corresponding to 
the selected position. 
Referring now in detail to FIGS. 2 and 6, in correspondence of the 
depression 8 of the front portion 7 of the body 2 an electrical control 
unit, generally designated as 20, is seated which completes the profile of 
the front portion 7 of the body 2 and is flush with the upper and side 
surfaces thereof. 
The control unit 20 is including a series of control members through which 
the tractor driver can perform active operating thereof in a convenient 
and easy way, only with the hand corresponding to his arm resting on the 
arm rest 1. 
More particularly, on the upper face of the control unit 20 the following 
control members are arranged: 
a pair of first control keys 21 whose depression operates up-shifting or 
down-shifting of the speed ratio, respectively, in an electronically 
controlled power-shift transmission, of a known type, of the tractor; 
a triad of second control keys 22 whose depression enables selecting 
forward speed, reverse speed (through the known electronically controlled 
reversing gear of the power-shift transmission) and the neutral condition 
of the tractor, respectively; 
a triad of third control keys 23 which can be used respectively to store or 
recall a maximum value or a minimum value of the rotation speed of the 
tractor engine, or for maintaining the current rotation speed, via an 
electronically controlled device, also of a conventional type, of the 
rotation speed. To the triad of third keys 23 a visual display 24 is 
operatively associated, for displaying when storage has been carried out 
and for displaying the on-off condition of the electronic control device 
of the engine rotation speed; 
a pair of fourth control keys 25 which can be actuated to operate raising 
and lowering of the electronically controlled power lift of the 
three-point hitch of the tractor, respectively. 
The control keys 21, 22, 23, 25 and the display 24 are operatively 
connected to respective electrical or electronic circuits, housed within 
the control unit 20 and in turn connected to the respective controlled 
systems (electronic control devices of the power shift transmission and 
associated reversing gear, electronic control device of the engine 
rotation speed, electronic control device of the power lift of the rear 
three-point hitch, respectively). 
In case the agricultural tractor is further provided, even in a known way, 
with an electronically controlled adjustment or fine correction device of 
the engine rotation speed, an additional manual control member for this 
device is contemplated, which is constituted by a knurled roller 26 
rotatably connected to the bottom of the control unit 20 and housed within 
a lateral seat 27 formed in the inner side of the front portion 7 of the 
arm rest body 2. This roller 26 may for instance be part of an optical 
encoder operatively connected to an electrical or electronic circuit 
contained within the control unit 20 and in turn connected to the 
electronically controlled fine adjustment device of the rotation speed of 
the tractor engine. 
To the aim of preventing accidental or undesired actuation of the various 
control members of the arm rest 1 disclosed in the above, a consent push 
button 28 (FIGS. 1 and 6) is also provided fort projecting downwardly from 
the front portion 7 of the body 2, beneath the control unit 20. The push 
button 28, which can be readily operated by one operator's finger, is 
operatively connected to the control unit 20 and enables, according to the 
set position thereof, inhibiting or enabling activation of this control 
unit 20, respectively. 
The alternative embodiment shown in FIGS. 7-13, wherein parts which are 
identical or similar to those already disclosed are indicated with the 
same reference numerals, differs from the embodiment of FIGS. 1-6 
essentially in that, further to adjustment of the inclination and 
adjustment of the longitudinal position (whose components already 
previously disclosed have been omitted for the sake of simplicity of 
illustration), the body 2 of the arm rest 1 is also angularly adjustable 
relative to the support plate 3 around a substantially vertical axis. 
In detail, according to this variant the bracket 13 is divided into an 
upper bracket portion 13a and a lower bracket portion 13b, to each of 
which a respective transverse plate 30, 31, respectively, is fixed by 
welding. The two plates 30, 31 are parallel to each other and bear one 
against the other in a mutually rotatable way, such as explained 
herebelow. 
The plates 30, 31 are connected therebetween by means of a pivot pin 33 
whose axis defines the above substantially vertical axis around which the 
body 2 of the arm rest 1 is rotatable relative to the support plate 3. For 
the angular adjustment of the body 2 around the axis of the pivot 33, a 
releasable locking member is provided, which is formed by a L-shaped lever 
34, shown in detail in FIGS. 11 and 12, comprising an arm 35 and a 
manoeuvring handle 36 perpendicular to the arm 35. This arm 35 has an 
eccentric portion 37 rotatably engaged within a bush 38 fixed below to a 
bolt 39 which is fitted across an arcuate slot 40 of the lower plate 31. 
The bush 38, which has an outer prismatic shape, is fitted into an opening 
41 formed in the upper plate 30 above the slot 40. 
The end of the arm 35 opposite to the manoeuvring handle 36 in provided 
with a radial pin 42 the function of which is both to prevent axial 
withdrawal of the arm 35 relative to the bush 38, and to stop rotation of 
the lever 34 from the raised locking position shown in FIG. 8 and FIGS. 7 
and 10, to the lowered unlocked position shown with dotted lines in FIGS. 
7 and 10. In the raised locking position the eccentric portion 37 
co-operates with the bush 38 so as to pack the plates 30 and 31 
therebetween via the bolt 39, so as to prevent relative angular 
displacement thereof. In the lowered unlocked position the plate 30, the 
upper bracket portion 13a along with the body 2 of the arm rest 1, are 
free to rotate around the axis of the pivot 33 relative to the plate 31 of 
the lower bracket portion 13b, and thus relative to the support plate 3, 
for an angular extent delimited by the extension of the slot 40 across 
which the bolt 39 is fitted. This angular extent can be for instance of 
about 23.degree. and defines the lateral adjustment range of the body 2 
around the axis of the pivot 33. 
With this arrangement, the position of the control unit 20 can be to 
advantage fully adapted and adjusted to the tractor operator's need, thus 
ensuring optimum operation comfort. 
FIG. 7 depicts also in better detail the cooperation between the rotatable 
threaded stop member 15 and the lower bracket portion 13b, for the 
adjustment of the body 2 of the arm rest 1 around the horizontal 
transverse axis 14. As it is apparent from this figure, the stop member 15 
has a threaded stem 43 screwed into a nut 44 fixed to the support plate 3, 
and adapted to frontally bear under pressure at its free end against a 
circular element 45 secured at the corresponding edge of the lower bracket 
portion 13b. 
Naturally the details of construction and the embodiments may be widely 
varied with respect to what has been disclosed and illustrated, without 
thereby departing from the scope of the present invention. Thus, for 
example, it is evident that the number, the arrangement and the functions 
of the various control members associated to the unit 20 carried by the 
arm rest 1 might be different from those disclosed by way of example, 
without thereby altering the advantageous effect deriving from the 
invention in terms of better convenience and comfort of active operating 
of the agricultural tractor afforded by the arm rest and incorporated 
control unit according to the invention.