Believe it or not, a relatively small pneumatic device helps farmers feed a hungry world as well as put more money in their pockets. Installed on seed planters, the advanced height-control module boosts farmers’ crop yields by letting them maintain a consistent seed depth from their tractor cabin. The mechanism works to control seed handling, seed placement and down/up-force.
Interestingly, the technology first arose in the transportation industry. Vehicles such as buses typically have a pneumatic component that lowers them so passengers can more easily climb on and off. The systems typically comprised custom collections of electric air switches, pneumatic valves and other parts.
Our engineers put all the components into a module that houses them in a machined-aluminum anodized body. Activated by solenoids, pneumatic valves inflate and exhaust air bags mounted on the vehicle axes. A flick of the switch in the cab makes vehicles such as buses lower, tilt left or right or elevate to a higher position for road travel.
Our knowledge of vehicle suspension systems led us to develop a module designed specifically for agricultural equipment such as seeders. Farmers typically use the equipment for only a few days each calendar year, so the height-control modules were designed to be durable and reliable. Seeders mostly sit outside, often battered with rain, sleet and snow, so reliability is crucial. When farmers want to seed fields for the spring season, the equipment must work without a hitch. Durability comes into play because the module had to withstand the abuse it encounters when a piece of farm equipment is being dragged through unplowed fields.
To better understand how pneumatic modules for seeders work let’s take a quick peek at their history. When farm technology began to evolve in more developed areas of the world such as the U.S. and Europe, farmers used planter equipment comprising a drum covered with stick-like probes. Rolling the drum poked holes in the ground for seed. Later, tractors pulled the drum, letting more acreage be farmed faster. This was the first step to significantly boosting crop production.
Fig 1. Early seeder pneumatic systems included individual row air bags, such as the one shown, fed by a small air compressor.
Eventually, the drums were separated into rows and spring force was used to push seeds into the ground. Farmers manually adjusted the springs to provide the necessary force based on soil conditions. Unfortunately, the springs often broke or wore out. Worse yet, farmers had to waste time climbing out of the tractor to re-adjust each spring (up to 48 rows).
That’s when the engineering light bulb went on, so to speak. Based on the transportation design, early seeder pneumatic systems consisted of individual row air bags fed by a small electrically driven air compressor alone. The air compressor provided a consistent pressure and cycled when pressure needed to be higher or to make up for system leakage.
Fig 2. An air compressor driven by hydraulic components such as the one shown help support the automation of pneumatic down force control.
Farmers typically adjusted the compressor and then did not touch it again when planting began. For fields soft from rain, farmers lowered the compressor output before operation. The air bag system efficiently handled terrain changes. When the ground was uneven, the system exhausted air from the airbag on the lower side of the slope and forced air into the airbag on the higher side of the slope. Farmers liked the airbag system for its durability and depth consistency but wanted a way to change pressure based on ground hardness, as monitored by the planter, which they could adjust in the cab. This would boost crop yield and crop production even more.
According to the American Farm Bureau today’s farmers
This is Part 1 of a 2 Part series shared by Richard McDonnell, Business Development Manager, Parker Hannifin, Pneumatic Division