Agricultural Implements and Attachments

Agricultural Implements and Attachments

Chapter Introduction

This chapter covers the full range of agricultural implements and attachments you will be called upon to diagnose, maintain, and repair as an agricultural equipment technician. Mastering this area is essential for the Red Seal exam, as questions cover not only mechanical principles but also safety standards, adjustment calculations, and inspection procedures specific to each type of implement.

Agricultural implements fall into two main categories: mounted implements (attached to the tractor's three-point hitch) and drawn implements (equipped with wheels and hitched to the drawbar). This fundamental distinction influences all maintenance, adjustment, and safety procedures.

Classification of Agricultural Implements

Tillage Implements

Tillage represents the largest and most diverse category. You must be familiar with the following subcategories:

Moldboard Plows: Used for deep tillage (15 to 30 cm). Composed of plow bottoms including the moldboard, share, heel, and coulter. Depth adjustment is done through the hydraulic hitch and gauge wheels. The share's angle of attack should be checked each season.

Chisel Plows and Heavy Cultivators: Work at depths of 10 to 20 cm without turning the soil over. The shanks are fitted with trip springs for shock protection. Spring tension must be uniform across the entire working width.

Rotary Tillers: Use vertical rotors to break up the soil. Rotor speed (typically 200 to 400 rpm) must be matched to soil type. Power take-off (PTO) speed is generally 540 or 1000 rpm.

Seed Drills: Precision equipment requiring meticulous adjustments. Precision seeders use discs or fingers to select individual seeds. Seeding rate is calculated in kg/ha or seeds/linear metre.

Harvesting Implements

Mowers: Cutterbar or rotary types. Rotary disc mowers dominate the modern market. Disc peripheral speed must reach 70 to 90 m/s for a clean cut.

Balers: Round or square balers. Variable-chamber round balers produce bales 1.2 to 1.8 m in diameter. Bale density is adjusted through hydraulic or mechanical belt tension.

Combine Harvesters: Complex equipment combining cutting, threshing, separation, and cleaning. Concave adjustment, rotor speed, and fan speed are critical for minimizing losses.

Haymaking Implements

Tedders and Rakes: Prepare forage for drying. Rotary finger rakes must be adjusted to avoid losing protein-rich leaves.

Windrowers: Gather forage into windrows. Windrow width is adjusted by the angle of the windrower wheels.

Hitches and Three-Point Linkage

Hitch Categories

The three-point hitch is standardized according to ASAE S217.12 (adopted by ANSI). Four categories exist, defined by pin diameters and hitch point geometry:

Common Trap: Do not confuse hitch category with tractor power. A 100 kW tractor may have a Category 2 or 3N (narrow) hitch. Always check manufacturer specifications.

Hitch Geometry

The triangle formed by the three hitch points must be isosceles for proper operation. Lower link arms must be equal in length, and top links must be adjusted so the implement is parallel to the ground.

The top link (upper arm) controls the implement's angle of attack. A top link that is too short raises the rear of the implement; a top link that is too long lowers the rear. General rule: for a plow, the top link should be adjusted so the frame is parallel to the ground when the shares are at working depth.

Lift Capacity Calculation

Lift capacity at the standard hitch point (610 mm behind the hitch points) is provided by the manufacturer. To calculate the overturning moment:

Overturning Moment (N·m) = Implement Mass (kg) × 9.81 (m/s²) × Distance from Centre of Gravity to Hitch Point (m)

The overturning moment must not exceed the rated lift capacity. An implement that is too heavy or too long can cause the tractor to tip backward.

Power Transmission: Power Take-Off (PTO)

PTO Types

Important Rule: The engine speed required to achieve rated PTO speed varies by tractor. Consult the manufacturer's manual. For example, some tractors reach 540 rpm at the PTO at 1800 engine rpm, others at 2100 rpm.

Driveline (PTO) Shafts

The driveline shaft must operate at a maximum angle of 15° during continuous operation and 25° during intermittent operation. Beyond this, universal joints wear prematurely and dangerous vibrations develop.

Shaft Length Calculation: The shaft must have a minimum overlap of 150 mm between the two halves when the implement is in its lowest position. In the highest position, a minimum clearance of 50 mm must remain to prevent tube compression.

Shaft Guarding: The shield (guard) must rotate freely and completely cover the shaft and joints. According to the Canadian Electrical Code, Part I (for related electrical installations) and CSA standards, guarding of power transmission components is mandatory. A damaged shield must be replaced immediately, never temporarily repaired.

Hydraulic Systems on Implements

Hydraulic Cylinders

Agricultural implements use single-acting or double-acting cylinders. Calculating cylinder force:

Force (N) = Pressure (Pa) × Piston Area (m²)

Piston Area (m²) = π × (Diameter/2)²

For a double-acting cylinder, the rod-side area is reduced by the rod cross-section:

Rod-Side Area = π × ((Diameter/2)² − (Rod Diameter/2)²)

Example: A cylinder with a 63 mm (0.063 m) diameter under a pressure of 180 bars (18,000,000 Pa):

Control Valves and Hoses

Hydraulic hoses are classified according to SAE J517 and must be replaced according to manufacturer recommendations (generally 5 to 7 years). ISO 5675 (single-handle) and ISO 7241 (push-type) quick couplers are the most common.

Hose Inspection: Examine each hose for bulges, cuts, abrasion wear, and hardening. A hose with visible wire reinforcement must be replaced before use.

Adjustments and Inspection Procedures

Pre-Season Inspection Procedure

Working Depth Adjustment

Working depth is adjusted using three complementary methods:

Practical Rule: For a 20 cm plowing depth, the gauge wheel should be set 20 cm below the level of the shares when the frame is horizontal.

Seeder Adjustment

Seeding rate is calculated as follows:

Seeding Rate (seeds/m²) = (Mass Seeded (kg) × 1000) / (TKW (g) × Area (m²))

Where TKW = Thousand Kernel Weight.

Example: To seed wheat at 150 kg/ha with a TKW of 40 g:

Seeder adjustment is verified by performing a test over a known area (e.g., 100 m²) and weighing the quantity of seed dispensed.

Safety and Standards

Applicable Safety Standards

Agricultural implements must comply with the following standards:

Rule 8-200 of the Canadian Electrical Code: Conductors and cables must be protected against mechanical damage. On agricultural implements, this means all wiring must be routed in conduits or protective sheathing.

Transport Safety

Agricultural implements transported on public roads must be equipped with:

The maximum transport width is 2.6 m on public roads in Canada (except provincial exemptions — check local regulations). Beyond this, a special permit is required.

Safety Chain Inspection

Safety chains must be crossed under the drawbar and secured to the tractor. Length must allow full turning without excessive tension. The load capacity of each chain must be at least equal to the gross mass of the implement.

Diagnosing Common Faults

Abnormal Vibrations

Loss of Hydraulic Power

Premature Wear of Parts

Premature wear of shares or shanks often indicates:

Preventive Maintenance

Recommended Maintenance Schedule

Winter Storage

Common Pitfalls to Avoid

Summary

Agricultural implements and attachments constitute a broad field requiring in-depth knowledge of mechanical, hydraulic, and safety principles. For the Red Seal exam, remember the following key points:

Mastering these concepts, combined with the ability to perform basic calculations (force, moment, seeding rate), will allow you to approach exam questions with confidence. Never forget that safety is paramount: every diagnostic or repair procedure must begin with a risk assessment and the application of appropriate protective measures.