A valve arrangement (2a, 2b) of a hydraulically braked tractor vehicle for controlling the brake pressure of a pneumatically braked trailer includes an electronically controlled trailer control valve (6) with an inlet valve (14), an outlet valve (16), a pneumatical relay valve (18), a breakaway valve (20) and a brake control pressure sensor (24). The valve arrangement also has a hydraulically controlled backup valve (8) with a hydraulically activated relay valve (46), a redundancy valve (112, 112′) and a hydraulic control pressure sensor (50). Output-side brake control lines (40; 62) are connected via a shuttle valve (10) to a brake coupling head (82). The valves (14, 16, 18, 20) and the pressure sensors (24, 50) of the trailer control valve (6), the valves (46, 112, 112′) of the backup valve (8) and the shuttle valve (10) may be combined in one trailer control module (98) with a single housing (100).

A hydraulic arrangement for connecting a tractor hydraulic brake circuit to a trailer hydraulic brake circuit is disclosed. The hydraulic arrangement includes a coupler stage fluidly connecting a source of fluid in pressure to the trailer braking hydraulic circuit and a trailer brake valve fluidly connecting the tractor hydraulic brake circuit and the trailer hydraulic brake circuit. The hydraulic arrangement further includes a selection pilot stage fluidly connected to the source of fluid in pressure and being fluidly connectable to the trailer hydraulic brake circuit via at least a connector and a selection stage fluidly connected to the selection pilot stage and to the trailer brake valve. The selection stage being configured to impart an actuation signal to the trailer brake valve in function of an hydraulic signal coming from the selection pilot stage.

A system for controlling a brake of a unit hauled by a work vehicle may generally include a valve assembly. When a speed of the work vehicle exceeds a predetermined speed threshold, the valve assembly may be configured to allow the brake to be actuated when first and second brake pedals of the work vehicle are depressed, either individually or simultaneously. However, when the speed of the work vehicle is less than the predetermined speed threshold, the valve assembly may only be configured to allow the brake to be actuated when both of the first and second brake pedals are depressed simultaneously.

In the event of a pneumatic trailer connection failure between a tractor and trailer of, e.g., a commercial vehicle, a pressure protection valve (PPV) is provided on the air line between a double check valve that supplies air from one or more service reservoirs and a trailer parking valve without a flow restrictor, which transmits the air to the trailer connection for supplying the trailer brakes. When output pressure on the PPV drops below a predetermined closing pressure threshold due to the connection failure, the PPV closes to protect the tractor brake air supply. Upon restoration of the trailer connection and upon input pressure at the PPV exceeding a predetermined opening pressure threshold, the PPV opens and the trailer brake system is charged more quickly than can be achieved using a conventional trailer parking valve with a flow restrictor.

A brake release system for a vehicle is described to transfer mechanical movement between two hydraulic actuators. The system includes a first hydraulic system on a removable portion of the vehicle and a second hydraulic system on a main chassis of the vehicle. The two hydraulic systems are mechanically engaged with each other where the removable portion of the vehicle attaches to the main chassis. In this way, a force applied to the removable portion of the vehicle when the vehicle's tow hook is engaged may be transferred to release the parking brake on the main chassis without a hydraulic connection between the removable portion and the main chassis. This may be useful when a removable battery frame with a tow hook makes up a separable rear portion of an electric vehicle, allowing the battery frame to be quickly and efficiently removed from the main chassis of the vehicle.

In an embodiment, a vehicle makes a determination, during a second ignition-on cycle of the vehicle, that a trailer brake output circuit of the vehicle was operated during a first ignition-on cycle of the vehicle preceding the second ignition-on cycle. In response to making the determination, the vehicle presents a query, via a user interface of the vehicle, whether to operate the trailer brake output circuit according to a previously-used trailer profile according to which the trailer brake output circuit was operated during the first ignition-on cycle preceding the second ignition-on cycle. The vehicle receives a reply, associated with the query, via the user interface and, in response to receiving the reply, operates the trailer brake output circuit based on the reply.

A method for driving a parking brake of a vehicle (V) wherein: for a setpoint between 0 and C1, the control pressure (200) is zero, and the supplementary pressure (100) is nonzero constant; for a setpoint between C1 and C3, the control pressure is proportional to the setpoint, for a setpoint between C2 and Cmax, the supplementary pressure is zero;
said values being such that

0<C1<C2<Cmax, and

0<C1<C3<Cmax.

A method of brake control of a vehicle combination (2) composed of a tractor vehicle (4) with an electronically controlled braking system (5) and a trailer vehicle (6, 8) with a pneumatically controlled pneumatic braking system (7, 9), involves introducing the brake control pressure (p.sub.BC) of the trailer vehicle (6, 8) into a tractor brake control line (19) extending to a tractor vehicle-side “brake” coupling head (26) via an electronically controlled trailer control valve (13) of the tractor vehicle (4). At the beginning of a braking operation, a pressure pulse (34) exceeding a target brake control pressure (p.sub.BC_soll) is introduced into the tractor brake control line (19). The volume of a trailer brake control line (28, 29, 32) coupled to the “brake” coupling head (26) is ascertained, and the absolute value (Δp.sub.PI) and/or the duration (Δt.sub.PI) of the pressure pulse (34) introduced are/is established depending on the ascertained volume.

Hydraulic arrangement for connecting a tractor hydraulic brake circuit to a trailer hydraulic brake circuit, comprising a coupler stage fluidly connecting a source of fluid in pressure to trailer braking hydraulic circuit and a trailer brake valve fluidly connecting the tractor hydraulic brake circuit and the trailer hydraulic brake circuit, the hydraulic arrangement further comprising a selection pilot stage fluidly connected to the source of fluid in pressure and being fluidly connectable to said trailer hydraulic brake circuit via at least a connector and a selection stage fluidly connected to the selection pilot stage and to the trailer brake valve, the selection stage being configured to impart an actuation signal to the trailer brake valve in function of an hydraulic signal coming from the selection pilot stage.

A brake module for a hydraulically braked tractor coupled to a pneumatically braked trailer has a trailer control valve connected via hydraulic control inlet to a hydraulic pressure line leaving a master brake cylinder, and via pneumatic inlet to a compressed air reservoir. Hydraulic control pressure determines pneumatic output pressure level at a trailer control valve pneumatic outlet. The brake module has a break-off prevention module which, if the control line leaks or separates from the trailer control valve relative to the trailer brake system, closes a supply pressure coupling head supply line and causes trailer brake system venting. The break-off prevention module has a pneumatic supply pressure inlet and a pneumatic tear-off control pressure inlet connected to the air reservoir independently of trailer control valve pressure inlets. Supply pressure inlet supply pressure passes through the break-off prevention module and feeds to a trailer control valve pneumatic supply pressure inlet.