Neutral start and park brake safety interlock circuitry for a tractor

• US 4,051,915 A
• Filed: 11/05/1976
• Issued: 10/04/1977
• Est. Priority Date: 11/05/1976
• Status: Expired due to Term

• Current Assignee: Deere & Company
• Original Assignee: Deere & Company
• Inventors: Behrens, Robert Nick
• Primary Examiner(s): Betts, Kenneth H.
• Application Number:
  US05/739,077
• Time in Patent Office: 333 Days
• Field of Search: 180/82 R, 180/82 A, 180/82 B, 180/82 C, 56/10.5, 123/179 R, 123/179 K, 123/179 SE, 307/9, 307/10 R, 74/473 R, 192/4 A
• US Class Current: 180/271
• CPC Class Codes: B60K 28/00 Safety devices for propulsion-unit control, specially adapted for, or arranged in, vehicles, e.g. preventing fuel supply or ignition in the event of potentially dangerous conditions for electrically-propelled vehicles B60L3/00; road vehicle drive control systems for purposes not related to the control of a particular sub-unit B60W30/00; drive control systems specially adapted for autonomous road vehicles B60W60/00
• CPC Class Codes: B60K 28/10 responsive to conditions relating to the vehicle
• CPC Class Codes: B60W 2510/0208 Clutch engagement state, e.g. engaged or disengaged
• CPC Class Codes: Y10T 74/20085 Restriction of shift, gear selection, or gear engagement

Abstract

Electric control circuitry is provided for preventing a tractor engine from being started with the tractor transmission or power take-off engaged and for preventing the tractor from being driven with the park brake engaged. The control circuitry includes normally open power take-off and transmission condition sensing switches connected in series with each other and a starting solenoid and thus defining a portion of a starting circuit. These two switches in the starting circuit are respectively held closed only when a power take-off control lever is in a clutch-disengage position and the transmission shift lever is in a neutral position. The control circuitry also includes a second normally open transmission condition sensing switch connected in parallel with a normally open park brake condition sensing switch, these two switches being in series with the ignition coil and thus defining a portion of an ignition circuit. Also, these two switches are respectively held closed only when the transmission shift lever is in its neutral position and a brake pedal locking pawl is in a pedal-release position.

Claims

1. In combination with a lawn and garden tractor including an electrically responsive engine starting means and an ignition means, a transmission shift means movable between neutral-effecting and drive-effecting positions, park brake control means movable between park brake release and park brake engage positions, and a power take-off clutch control means movable between clutch-engage and clutch-disengage positions, a safety interlock circuit, comprising:

a source of electric energy;

an ignition switch means connected to the source;

a starting circuit including a first lead means connected between the ignition switch means and the engine starting means;

a normally open power take-off clutch condition responsive switch means mounted for actuation to a closed position by the clutch control means only when the latter is moved to its clutch-disengage position;

a first normally open transmission condition responsive switch means mounted for actuation to a closed position by the transmission shift means only when the latter is moved to its neutral-effecting position;

said clutch condition responsive switch means and first transmission condition responsive switch means being connected between the ignition switch means and the engine starting means in the first lead means in series with each other and with the ignition switch means and the engine starting means;

an ignition circuit including a second lead means connected to the ignition switch means and the ignition means;

a second normally open transmission condition responsive switch means mounted for actuation to a closed position by the transmission shift means only when the latter is moved to it neutral-effecting position;

a normally open park-brake condition responsive switch means mounted for actuation to a closed position by the park brake control means only when the latter is moved to its park brake disengage position; and

said second transmission condition responsive switch means and said park brake condition responsive switch means being connected in said second lead means between the ignition switch means and the ignition means in parallel to each other, whereby the tractor cannot be started with the transmission or power take-off clutch engaged or driven with the park brake engaged.