This invention relates to a joystick arrangement for selectively actuating a group of four spool valves for controlling a plurality of functions of hydraulically operated equipment such as a tractor-mounted loader or excavator.

Such arrangements are already known, one of which comprises a base-plate, a handle connected by a universal joint to the base-plate, four valve-actuating plungers slidably disposed in the base-plate at right angles around the universal joint and four balls connected to a plate secured to the handle and engaging closely in respective sockets fixed to the adjacent ends of the plungers. The sockets serve also as armatures of solenoid means which include coils surrounding the respective plungers.

The known arrangements typified by that described in the preceding paragraph have disadvantages including relative bulkiness, expense, difficulty of assembly, and high friction. It is also difficult to control one valve without interfering with the operation of any adjacent valve which is wholly or partly open.

The object of the present invention is to mitigate the latter of the aforesaid disadvantages. Mitigation of the remaining disadvantages are addressed by preferred embodiments of the invention.

According to the invention, a joystick arrangement for selectively actuating a group of valves comprises a base¬ plate, at least two valve-actuating plungers slidably disposed in the base-plate, a handle mounted on the base¬ plate and capable of pivoting with respect to the base¬ plate about two axes, and at least two pins projecting from the handle and engaging the adjacent ends of respective plungers, the engagement between each pin and the adjacent

end of its respective plunger being such that movements of the pin parallel to the axis along which its respective plunger slides are transmitted to the plunger, but movements of the pin of similar magnitude perpendicular to that axis are not.

The handle is connected to the base-plate by a universal joint.

Preferably, for convenience of use, the relative angular position of the valve-actuating plungers about the universal joint is 90 degrees.

The ends of the pins may engage in slots in the adjacent ends of their respective plungers.

There may be two plungers in the base-plate, disposed at right angles to each other around the universal joint. There may be three plungers in the base plate, around the universal joint, but preferably there are four such plungers.

Preferably, when four pins are present, they are carried in a cruciform configuration by the handle and the slots are formed at the adjacent ends of the plungers and disposed generally perpendicularly to the longitudinal centre-lines thereof. When two pins are present there may be a similar arrangement, but with the pins being carried in an L-shaped configuration by the handle. When three pins are present there may be a similar arrangement, but with the pins being carried in a T-shaped configuration by the handle.

Preferably, also, the pins have spherical ends.

Solenoid means are preferably associated with the respective plungers for the purpose of holding down any one or adjacent two of the plungers which have been fully depressed by movement of the handle.

Preferably, coils for the solenoid means surround the respective plungers within the base-plate, and armatures for the solenoid means are mounted near the said ends of the plungers.

Preferably, also, the armatures are loosely mounted on the plungers.

The solenoid means are preferably permanently energised.

A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings of which:

Figure 1 is a side elevation of a joystick arrangement clamped to a valve block;

Figure 2 is a section on the line 2-2 in Figure 1;

Figure 3 is a view in the direction of the arrow 3 in Figure 1 showing the underside of the valve block;

Figure 4 is a sectional side elevation on a somewhat larger scale of the joystick arrangement and valve block on the line 4-4 in Figure 2; and

Figure 5 is a side elevation on a much larger scale of one of four pin-and=slot connections forming part of the joystick arrangement.

Referring now to the drawings, a joystick arrangement indicated generally at 10 is adapted to be clamped as shown to a valve block 12 slidably housing a group of four parallel spool values 14 which are spring-loaded towards the arrangement. When partially depressed against its spring-loading, each of the valves allows the passage of oil at an infinitely variable reduced pressure through one of the ports 16 to a main control valve (not shown), thus

acting as a pilot valve. The valve block 12 has an oil inlet port 18.

A flange 22 of the joystick arrangement 10 is adapted to be clamped to a similar flange 24 on the valve block 12 by means of four bolts (not shown) passing through aligned holes 26 in the flanges. A handle 28 is connected by a universal joint 30 to a short post 32 screwed into the centre of the base-plate 20. Four plungers 34 are slidably and rotatably disposed in the base-plate 20 at right angles around the post 32 carrying the universal joint 30, in alignment and in end-to-end contact with the respective spool valves 14.

Pin-and-slot connections between the handle 28 and the adjacent ends of the respective plungers 34 comprise pins 36 carried in a cruciform configuration by the handle and slots 38 formed in small plates 40 secured to the adjacent ends of the plungers. The slots 38 are disposed generally perpendicularly to the longitudinal centre-lines 42 of the plungers 34, but have freedom to turn thereon and the pins 26 have spherical ends 44, which are a close sliding fit in the slots 38.

Solenoid means associated with the respective plungers 34 include coils 46 which surround the plungers within the base-plate 20 and are permanently energised by an electrical current supplied by way of insulated cables 48. The solenoid means also include armatures in the form of annuli 50 which are mounted near the aforesaid ends of the plungers 34 directly beneath the plates 40. The annuli 50 are loosely mounted on the plungers so as to make optimum contact with the tops of the coils 46.

A corrugated rubber boot 52 encloses the joystick arrangement 10 from the base-plate 20 to the lower end of a hand grip 54 on the handle 28.

In operation, the joystick arrangement 10 has two axes of movement (or degrees of freedom) whereby any one or adjacent two of the plungers 34 can be partially or fully depressed at one time to actuate the associated spool valves 14. When any one of the plungers is fully depressed it is held down by its associated solenoid means whilst complete freedom of movement of the handle 28 about the other axis is retained to permit depression of either one of the two adjacent plungers 34 as required. The pin-and- slot connections permit this because each spherical end 44 can move laterally along its slot 38 as well as co-acting with the upper or lower walls of the slot to move the associated plunger 34 up or down.

When any adjacent two of the plungers 34 are both fully depressed at one time, they are held down by their associated solenoid means whilst the handle 28 is held in a fixed position and the other two plungers 34 cannot be moved. The application of sufficient manual force to the handle 28 operates to pull a plunger 34 out of the detaining influence of the associated solenoid means.

Thus there is provided, by the provision of the pin-and- slot connections, a joystick arrangement which is neat and compact, relatively cheap, and easy to assemble, and which allows low friction movement of the handle, such movement being fully retained in one axis even when one of the plungers is held down by its associated solenoid means.