by GJ Stoltz (Reg Eng Tech)

This month we move into the field where the hay is cut and already dried, to start with the baling operation. Baling can begin when the windrows are ready. Bale the driest hay first. The baler should move in the same direction that the rake had gone, because this helps the pick-up teeth to reach under the windrow and pick up the hay in a “head-first” position.

Lower the pick-up before engaging the baler-drive clutch. Bring the engine up to the recommended speed before starting to pick up hay. Drive in a low gear for a short time to make sure that the baler is functioning properly. When starting with an empty bale chamber, the first few bales will be light and their length irregular.

The productivity of a baler depends on crop characteristics, ground conditions, condition of the tractor and baler and the judgement of the operator. Do not overcrowd the baler. If the feeding mechanism is properly adjusted and still cannot handle the incoming hay, the baler is being crowded beyond its capacity and serious damage may result. Reduce the ground speed, but maintain the recommended PTO speed for proper baler operation. Always run the tractor’s engine fast enough to maintain a proper baler operating speed. When turning on the headlands, disengage the tractor’s PTO to avoid excessive vibration.

Keep the twine and wire tying mechanisms as well as the plunger safety stop clean from chaff. Accumulation of chaff on the bale measuring trip device results in long and untied bales.

Field adjustments

When a malfunction occurs, always analyse the situation before taking action.

For example, a baler may occasionally miss tying a bale. Unless a true malfunction pattern is established, the condition may be only temporary and require no corrective action. If broken bales must be rebaled in the field, the original wires or twines must be removed and the hay spread out so that it can be picked up again. Do not hand feed broken bales into the baler because it is very dangerous and somebody can lose an arm in the process.

Pick-up adjustments:

Adjust the pick-up of the baler until a clean pick-up from the stubble is achieved. Normally the teeth are set to operate just below the top of the stubble, but not low enough to hit the ground. If the pick-up’s teeth strike the ground, they may bend backward and when recoiling they will shatter leaves and mix dirt with the hay (see Picture 3 and Figure 1). A pick-up gauge wheel is available for some balers that prevents such problems and helps the pick-up to follow the ground contour (see Picture 4).

Feed rake adjustments:

Most balers have feeder teeth to move hay from the auger into the bale chamber. Some balers don’t have augers and use only their feed rakes to feed the hay from the feeder compartment into the bale chamber. The rake’s movement must be such that uniform bales are produced. If the feed rake is improperly adjusted, more hay will be packed onto one side of the bale than the other.

This usually results in one wire, or twine, being pulled tighter than the other and causes “banana” bales, which are very unstable (see Picture 5).

If the feeder teeth on the feed rake are set to their longest stroke and material is still not going far enough into the bale chamber, the baler is probably being underfed and the land speed must be increased or the windrows must be combined. Always consult the operator’s manual when adjusting the feeder teeth. The feeder teeth on some balers are called the “packer cross-feeding system” and the plunger is called the “ram” (see Figure 2).

Bale weight

Bale weight is effected by the size of the windrows, moisture content and the quality of the hay. Since these factors may vary from hour to hour, or from windrow to windrow, the bale weight should be checked regularly during the operation. To regulate bale weight, change the tension on the bale chamber by adjusting the two tension cranks at the rear of the chamber. This pulls the upper and lower tension bars together and restricts the hay passage through the bale chamber. Hydraulic bale tension control is available for some balers and can provide on-the-go control of the bale weight (see Picture 6).

Bale density may be further increased by installing hay resistors in the bale chamber, especially when baling fluffy hay or very light windrows. Hay resistors slow the passage of material through the bale chamber and prevent it from bouncing back between plunger strokes. They are very helpful when baling straw (see Figure 3).

The resistors must be removed when baling normal hay again to avoid un­necessary strain on the baler caused by the extra resistance. The tension cranks must be released at the end of each day’s operation to relieve the tension springs and to reduce the possibility of bales sticking in the bale chamber. If bales left in the bale chamber get wet with rain, the material will expand and cause problems when restarting the baler.

Bales that are too tight or too heavy put excessive strain on the baler and can break parts, twine and wire. Hay bales normally weigh between 22 kg and 25 kg.

Measuring wheel

A measuring wheel with prongs, projecting into the forming bale, rotates as the compressed hay moves to the back of the bale chamber. After the wheel has turned a certain distance, the tying mechanism is tripped and the needles take the twine, or wire, to the knotters to complete the tying of the bale. Irregular-length bales come from inconsistent hay density. Make the density more consistent by increasing the land speed, increasing the size of the windrow or tightening the bale tension cranks.

Flywheel shear bolt

The shear bolt on the flywheel will shear if the plunger is blocked. After the blockage is cleared up, replace the shear bolt with a new one. Use only shear bolts recommended by the manufacturer.

Do not replace a shear bolt with a standard bolt. Bolts that are too soft will shear unnecessarily and waste time. Bolts that are too hard may not shear when needed and will not provide protection. If the needles are in the bale case when the bolt shears, return the needles to the “home” posi­tion by hand before starting the baler. Before starting the baler, the flywheel must be turned by hand through a complete plunger cycle to make sure all components are functioning prop­erly and no obstructions are blocking the operation.

We thank the ARC Agricultural Engineering in South Africa who made the information on square balers available to the readers of ProAgri Zambia. Next month we shall look at baler attachments. Visit www.arc.agric.za for more information.