Electro-Hydraulic Control of Combine Header Height and Reel Speed

Combine electro-hydraulic header height control systems have been widely accepted. Conventional on-off solenoid valves, however, perform less than ideally in automatic header height control systems due to their lack of metering. More acceptable automatic mode performance can be achieved with two stage valving, with a controlled response solenoid valve, or using a proportional valve.

Electro-hydraulic proportional flow limiters provide smooth, repeatable flow control for combine hydraulic reel drives. Manual control options include a rheostat, a stepped resistance switch, or a pulse width modulated circuit. Automatic correlation of reel speed to ground speed is achieved with a closed loop or open loop electronic system.