Braking equipment

Claim 2

Braking equipment having a dynamic braking system and a fluid pressure braking system including a brake pipe, the fluid pressure in which serves to control the degree of braking effected by the fluid pressure braking system, the equipment comprising: a converter means for converting into an output fluid pressure an electrical input signal, the value of which input signal is indicative of the degree of braking being effected by the dynamic braking system and the value of which output fluid pressure corresponds to the value of the input signal; the source of supply of fluid pressure to the converter means from which source the converter means derives said output fluid pressure being the fluid-pressure of the brake pipe, pressure-responsive means for comparing with said output pressure a master fluid pressure indicative of the degree of braking required to be effected by the equipment, and a valve means for producing an output pressure indicative of the excess, if any, by which the master pressure exceeds the output pressure, and means for effecting operation of the pneumatic braking system in response to the output pressure from the valve to a degree which is the difference between the degree of braking required to be effected by the equipment and the degree of braking being effected by the dynamic braking system.

Claim 3

Braking equipment as claimed in claim 1, wherein the converter means has an input port connected to the source of fluid pressure, an outlet port and an exhaust port; a cantilever-mounted arm to which is applicable a force the value of which is dependent upon the value of the input signal; and a throttling element associated with the exhaust port and arranged to be operated through said arm by said force variably to throttle the exhaust port in dependence upon the value of the force and thereby produce at the output port a back pressure the value of which is dependent upon the value of the input signal.

Claim 4

Braking equipment as claimed in claim 2, wherein there is interposed between the output port of the converter means and the pressure-responsive means, a relay valve by which the back pressure is relayed as the output pressure of the converter means to the pressure-responsive means.

Claim 5

Braking equipment as claimed in claim 3, wherein the relay valve is fed from a source of fluid pressure which also is the fluid-pressure in the brake pipe.

Claim 6

Braking equipment as claimed in claim 1, wherein the valve means together with the pressure-responsive means, constitutes a self-lapping valve means.

Claim 7

Braking equipment as claimed in claim 5, wherein the pressure-responsive means includes a plurality of pressure responsive elemEnts, to one of which is applied the master pressure and to two others of which are applied, respectively, the output pressure of the converter means and the output pressure of the valve means; the force exerted by the master pressure on its pressure-responsive element being opposed by the forces exerted by the two output pressures each on their respective elements.

Claim 8

Braking equipment as claimed in claim 1, wherein the valve means has an inlet port connected to a source of fluid pressure, an exhaust port and an outlet port through which is delivered the output pressure of the valve means, the soruce of pressure being the master pressure.

Claim 9

Braking equipment as claimed in claim 7, wherein the master pressure and the output pressure of the valve means are fed through first and second conduits, respectively, there being connected across the conduits in parallel with the valve means a one-way valve arranged to permit flow of fluid only in the direction from the second conduit to the first conduit.

Claim 10

Braking equipment as claimed in claim 1, wherein the pressure-responsive means includes a force-generating means operative to cause the valve means to deliver an output pressure from the valve means which is of low value sufficient only to prepare the fluid-pressure braking system for effecting braking operation by the fluid-pressure braking system, when the degree of braking effected by the dynamic braking system equals the degree of braking require to be effected by the equipment.

Claim 11

Braking equipment as claimed in claim 9, wherein the force-generating means is rendered inoperative by the degree of braking effected by the dynamic braking system being less than the degree of braking required to be effected by the equipment.

Claim 12

Braking equipment as claimed in claim 6, wherein the force generating means is rendered inoperative by the degree of braking effected by the dynamic braking system being less than the degree of braking required to be effected by the equipment, wherein the force-generating means is a spring operative in opposition to the output pressure from the valve means on that pressure-responsive element on which the output pressure from the valve exerts its force only for so long as the force is exerted by the master pressure and the output pressure are not equal.

Claim 13

Vehicle braking equipment having a dynamic braking system; signal-generating means by which is derived a first fluid a first fluid pressure output the value of which is indicative of the degree of braking being effected by the dynamic braking system; a fluid-pressure braking system from which is derived a second fluid pressure output the value of which is indicative of the degree of braking required to be effected by the equipment; variable-load means by which can be derived a third fluid pressure output the value of which is indicative of the load of the vehicle; inhibiting means by which said third output fluid pressure is inhibited from being so indicative; and self-lapping valve means comprising a valve the operation of which is controlled by forces exerted on the valve by pressure-responsive means to derive from an input pressure constituted by the second output fluid pressure a final fluid pressure output indicative of the degree of braking to be effected by the fluid-pressure braking system; the pressure-responsive means including a pressure-responsive system in which is compared said first and second fluid pressure outputs to produce a first force; a pair of pressure-responsive elements between which is applied said third fluid pressure output to generate on one of the elements a second force which, when the third fluid pressure output is indicative of the load of the vehicle, opposes and is greater than the first force and, in such specified condition, generates on the other element a third force indicative of the load of the vehicle; a further pressure-responsive element to which is applied said final fluid pressure output to generate a further force in opposition to Said third force; and between said other element of the pair of elements and the further element force-generative means exerting on the further element a fifth force of predetermined value which opposes the fourth force but which is rendered ineffective by the application between the pair of elements of said third pressure output when that pressure is indicative of the load of the vehicle.

Claim 14

Vehicle braking equipment having a dynamic braking system; signal-generating means by which is derived a first fluid a first fluid pressure output the value of which is indicative of the degree of braking being effected by the dynamic braking system; a fluid-pressure braking system from which is derived a second fluid pressure output the value of which is indicative of the degree of braking required to be effected by the equipment; variable-load means by which can be derived a third fluid pressure output the value of which is indicative of the load of the vehicle; inhibiting means by which said third output fluid pressure is inhibited from being so indicative; and self-lapping valve means comprising a valve the operation of which is controlled by forces exerted on the valve by pressure-responsive means to derive from an input pressure constituted by the second output fluid pressure a final fluid pressure output indicative of the degree of braking to be effected by the fluid-pressure braking system; the pressure-responsive means including a pressure-responsive system in which is compared said first and second fluid pressure outputs to produce a first force; a pair of pressure-responsive elements between which is applied said third fluid pressure output to generate on one of the elements a second force which, when the third fluid pressure output is indicative of the load of the vehicle, opposes and is greater than the first force and, in such specified condition, generates on the other element a third force indicative of the load of the vehicle; a further pressure-responsive element to which is applied said final fluid pressure output to generate a further force in opposition to Said third force; and between said other element of the pair of elements and the further element force-generative means exerting on the further element a fifth force of predetermined value which opposes the fourth force but which is rendered ineffective by the application between the pair of elements of said third pressure output when that pressure is indicative of the load of the vehicle.

Claim 15

Braking equipment as claimed in claim 12, wherein the fluid-pressure braking system is a system which is controlled by a fluid-pressure signal.

Claim 16

Braking equipment as claimed in claim 13, wherein there is additionally a further fluid-pressure braking system which is controlled both by an electrical signal and in dependence upon the load of the vehicle, the second output fluid pressure then being derived either from the system controlled by the fluid-pressure signal or from the further fluid-pressure braking system.

Claim 17

Braking equipment as claimed in claim 12, wherein there is positioned between the pair of pressure-responsive elements between which is applied said third output pressure, an abutment against which is urged said other of the elements by the resilient means.

Claim 18

Braking equipment as claimed in claim 12, wherein said other of the pair of elements carries a stem by which the force generating means is rendered ineffective when the third fluid pressure output is indicative of the load of the vehicle, by the stem engaging the further pressure-responsive element so that it thereby transmits to the further element the third force.

Claim 19

Braking equipment as claimed in claim 12, wherein the force-generating means operatively extends between said other of the pair of pressure-responsive elements and said further pressure-responsive element.

Claim 20

Braking equipment as claimed in claim 12, wherein, the signal-generating means is a converter by which an electrical input signal a value of which is indicative of the degree of braking being effected by the dynamic braking system, is converted into saie first fluid-pressure output.