BACKGROUND OF THE INVENTION

The invention relates to a feeler device, particularly but not exclusively for testing the flanks of gear teeth.

In a known feeler device for gear tooth flanks, the feeler pressure can be so changed over by a helical spring that it is possible at will to apply the device to a left-hand or a right-hand tooth flank. In making this change, due to the different stressing of the helical spring, depending on a winding or unwinding movement, differences in torque and thus in force occur with equal plus or minus angles of rotation.

The invention has for its object to provide a device in which the feeler pressure for left-hand and right-hand tooth flanks can be given the same value with equally large symmetrical deviation angles of the change-over member.

SUMMARY OF THE INVENTION

This object is achieved in the present invention by providing a displaceable member for biasing the device in a predetermined direction of deflection, the displaceable member being arranged to act on respective springs, in dependence upon its position of adjustment which urges the device into one or another alternative end position.

The displaceable member is preferably in the form of a rotatable ring and may be provided with an abutment surface providing a camming action to vary the setting of said springs. Such an abutment surface may take the form of an inclined plane on an end face of the ring and set obliquely to the direction of rotation of the ring.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the invention will be described, by way of example, with reference to the accompanying drawing, wherein:

FIG. 1 is a perspective view of the front portion of a feeler device according to the invention, and

FIG. 2 is a similar perspective view of the rear portion of the same device.

DESCRIPTION OF A PREFERRED EMBODIMENT

Referring to the drawing, the device comprises an elongated tubular carrier member 1 on which various elements of the device are mounted. These include a ring 2 that is rotatable on the forward end of the carrier member and has an inclined rear end face 3 obliquely inclined to its axis of rotation. The carrier member also supports two longitudinally extending pins 4 disposed symmetrically on opposite sides of the member 1. Slots 5 are provided on opposite sides of the carrier member 1, and in each slot is arranged a bell crank lever 6 mounted on the member 1 by pins 7. A leaf spring 8 is fixed by one end to each bell crank lever 6. A disc 9 on which contact segments 10 are arranged is also secured on the carrier member 1.

In front of the rotatable ring 2 there is fixed a disc 11, which carries a fiducial mark 12. A symmetrical scale 13 on the rotatable ring 2 co-operates with the mark 12.

Fixed in the base member 1 are two diametrically opposed flanges or mounting discs 14, in which are set two leaf spring 15 arranged perpendicular to one another. The central zone of these two leaf springs 15 passes through a cross bore in a lever or rod 16 extending centrally along the member 4, the lever thus being pivotable in a certain direction of deflection (in the horizontal plane as seen in the drawing). One end of the lever or rod projects forwards of the member 1 and carries a feeler probe 17 held in place by a tension spring 18 with pins 19 and 20. The form of interconnection permits articulation between the probe and the rod if there is an excessive side loading on the probe that cannot be taken up by deflection of the rod, the probe then pivoting on a side edge of the interface 21 between it and the rod, but the probe and rod normally move together.

Towards the rear of the rod 16 there is a collar 22 against which lateral pressure is applied by the leaf springs 8.

Screws 23 which are disposed on opposite sides of the rod 16 in the vertical plane and are arranged in the member 1 with some clearance from the rod, prevent the rod being tilted in the vertical plane. Spring stops 24, fixed in the base member 1, prevent excessive horizontal deflections of the rod 16 and also take up horizontal impacts of the rod.

Disposed in two diametrically opposed flanges or supports 25 set into the member 1 is a measuring pin 26, which establishes the horizontal position of the bar 16 by induction, the associated electric or electronic measuring elements being arranged in a housing 27. Connecting wires 28 lead from the housing to a plug socket 29 fixed in the rear of the member 1. A sleeve 30 encloses the mechanism from the rear of the member 1 to the ring 2 and a packing 31 protects it from dust.

When gear tooth flanks are to be tested by means of the device, then it is normally clamped in a suitable testing machine by the exterior surface of the sleeve 30 and the probe 17 is brought into contact with the chosen tooth flank. If it is the left-hand tooth flank which is concerned, then the rotatable ring 2 is set beforehand according to the scale 13 and the mark 12 for "left" to a specified bias. After a turning movement of the ring 2, the inclined end face 3 acting on the two pins 4 forces each one to a greater or lesser degree, corresponding to the preselected bias characterised by a number on the scale 13, against the bell crank lever 6 whereby the springs 8 are urged against the rod 16 with different pressures and deflect the rod about the springs 15 to one side in the horizontal plane. As a consequence, when pivoted to a maximum the rod comes to an end position against one or other of the spring stops 24.

If now the tooth flank to be tested presses in the opposite direction against the probe 17, then the feeler rod 16 experiences a pivotal movement in the horizontal plane back towards its central position or beyond and against the force of that one of the springs 8 biassing it from that position. The setting taken up by the rod is sensed and transmitted by the measuring pin 26 and the measuring elements in the housing 27 and the resulting electrical signals are emitted through the connecting wires 28 and the plug socket 29 to external indicating instruments or recording means. The contact segments 10 produce as a function the direction of rotation of diagram paper according to the left-hand flank, if the recording means are provided in diagram form.

If the right-hand tooth flank is to be tested, a similar procedure is used, the opposite one of the two pins 4 now being urged rearwards by rotational adjustment of the ring 2 to cause its associated spring 8 to pivot the rod 16 into the other end position.

It is also possible to employ similarly acting cams instead of an oblique face on the rotatable ring 2, which cams, arranged symmetrically, urge the pins 4 against the bell crank levers 6 and thus against the springs 8, according to the rotational setting of the ring.

The feeler device is not only capable of being used for testing tooth flanks, but can also be employed for other services in which the deflection of a feeler element has to take place in a specific direction.