Brake system condition warning system and switch assembly therefor

Claim 2

A brake system condition warning system comprising: first and second and third brake system condition sensors respectively sensing the presence and absence of first and second and third brake system conditions, first warning means actuated through at least one of said first and second sensors by the presence of at least one brake condition sensed by at least one of said first and second sensors, and second warning means actuated through a series connection formed through said first and second sensors by the presence of one and the absence of the other of said first and second brake conditions sensed by said first and second sensors, said second warning means also being actuated through said third sensor by the presence of said third brake system condition irrespective of said first and second brake system conditions.

Claim 3

The brake system condition warning system of claim 1, said first brake system condition being the brake-actuating pressurization of a first fluid pressure actuated brake system circuit system in the brake system, said second brake system condition being the brake-actuating pressurization of a second fluid pressure actuated brake circuit in the brake system, and said third brake system condition being the application of a parking brake.

Claim 4

The brake system condition warning system of claim 2, said first and second and third sensors respectively comprising first and second and third switches, each of said first and second switches having first and second and third contacts and means biasing sAid third contact into engagement with said first contact and pressure-responsive means fluid connected with a fluid pressure actuated brake circuit and actuable upon pressurization of the associated fluid pressure actuated brake circuit to move said third contact from engagement with said first contact to engagement with said second contact, said third switch being a normally open switch and having fourth and fifth contacts closed by application of a parking brake.

Claim 5

The brake system condition warning system of claim 3, further comprising: a source of electrical energy and means connecting said second and fourth contacts thereto, means connecting said third contacts to said first warning means, and means connecting said first and fifth contacts to said second warning means.

Claim 6

In a vehicle having first and second fluidly independent hydraulic brake circuits and means for pressurizing each circuit to actuate vehicle brakes, a vehicle multiple hydraulic brake circuit condition indicating system comprising in combination: a hydraulic circuit condition sensing assembly for sensing hydraulic fluid pressure conditions of each of said hydraulic circuits, the conditions being sensed being the presence and absence of predetermined hydraulic pressures in each of said hydraulic circuits when said pressurizing means are actuated, said sensing assembly comprising for each of said hydraulic circuits connected thereto: a hydraulic pressure responsive displacement member, means biasing said displacement member against hydraulic pressure in the hydraulic circuit connected thereto and being overcome at a predetermined minimum hydraulic pressure in the hydraulic circuit connected thereto and permitting displacement of said displacement member, a switch having first and second and third electrical contacts in aligned relation, said first and third contacts being spaced apart and receiving said second contact therebetween for displaceable movement between positions in which said second contact electrically engages said first contact, said second contact is electrically disengaged from said first and third contacts, and said second contact is electrically engaged with said third contact, said second contact being connected with said biasing means and being biased thereby into electrical engagement with said first contact, and being operatively connected to said displacement member to be moved out of electrical engagement with said first contact upon the displacement of said displacement member by the predetermined minimum pressure in said hydraulic circuit connected thereto, and being thereafter moved into electrical engagement with said third contact at a predetermined higher pressure in the hydraulic circuit connected thereto which causes further displacement of said displacement member against said biasing means, said biasing means returning said second electrical contact from electrical engagement with said third contact to electrical engagement with said first contact and returning said displacement member to its predisplaced position upon the decrease of hydraulic pressure in the hydraulic circuit connected thereto below said predetermined minimum hydraulic pressure; a vehicle brake having brake apply and release conditions independent of said hydraulic circuit conditions and being indicated by an operator-controlled switch which is open when the brake is released and is closed when the brake is applied; said sensing assembly having each of said first contacts for each of said hydraulic circuits electrically connected and each of said second contacts for each of said hydraulic circuits electrically connected and each of said third contacts for each of said hydraulic circuits electrically connected; first and second electrically energizable indicators; and a source of electrical energy having an electrical ground and an electrical energy output, said output being electrically connected to said third contacts and through sAid operator-controlled switch and through said first electrically energizable indicator to electrical ground; said second electrically energizable indicator having said second contacts electrically connected therethrough to electrical ground; said first contacts being electrically connected through said first electrically energizable indicator to electrical ground.

Claim 7

In a vehicle having first and second fluidly independent hydraulic brake circuits and means for pressurizing each circuit to actuate vehicle brakes, a vehicle multiple hydraulic brake circuit condition indicating system comprising in combination: a hydraulic circuit condition sensing assembly for sensing hydraulic fluid pressure conditions of each of said hydraulic circuits, the conditions being sensed being the presence and absence of predetermined hydraulic pressures in each of said hydraulic circuits when said pressurizing means are actuated, said sensing assembly comprising for each of said hydraulic circuits connected thereto: a hydraulic pressure responsive displacement member, means biasing said displacement member against hydraulic pressure in the hydraulic circuit connected thereto and being overcome at a predetermined minimum hydraulic pressure in the hydraulic circuit connected thereto and permitting displacement of said displacement member, a switch having first and second and third electrical contacts in aligned relation, said first and third contacts being spaced apart and receiving said second contact therebetween for displaceable movement between positions in which said second contact electrically engages said first contact, said second contact is electrically disengaged from said first and third contacts, and said second contact is electrically engaged with said third contact, said second contact being connected with said biasing means and being biased thereby into electrical engagement with said first contact, and being operatively connected to said displacement member to be moved out of electrical engagement with said first contact upon the displacement of said displacement member by the predetermined minimum pressure in said hydraulic circuit connected thereto, and being thereafter moved into electrical engagement with said third contact at a predetermined higher pressure in the hydraulic circuit connected thereto which causes further displacement of said displacement member against said biasing means, said biasing means returning said second electrical contact from electrical engagement with said third contact to electrical engagement with said first contact and returning said displacement member to its predisplaced position upon the decrease of hydraulic pressure in the hydraulic circuit connected thereto below said predetermined minimum hydraulic pressure; a vehicle brake having brake apply and release conditions independent of said hydraulic circuit conditions and being indicated by an operator-controlled switch which is open when the brake is released and is closed when the brake is applied; said sensing assembly having each of said first contacts for each of said hydraulic circuits electrically connected and each of said second contacts for each of said hydraulic circuits electrically connected and each of said third contacts for each of said hydraulic circuits electrically connected; first and second electrically energizable indicators; and a source of electrical energy having an electrical ground and an electrical energy output, said output being electrically connected to said third contacts and through sAid operator-controlled switch and through said first electrically energizable indicator to electrical ground; said second electrically energizable indicator having said second contacts electrically connected therethrough to electrical ground; said first contacts being electrically connected through said first electrically energizable indicator to electrical ground.