This chapter covers all the skills required for the safe and efficient operation of a tractor-loader-backhoe loader. For the Red Seal exam, you must master not only the controls and loading techniques, but also the physical principles that govern stability, lifting capacity, and productivity. This chapter is structured according to the competency blocks of the National Occupational Analysis (NOA) for heavy equipment operators.
2. Fundamental Principles of the Loader
2.1 Definition and Role of the Loader
The loader is the equipment mounted on the front of the tractor-loader-backhoe, consisting of two parallel hydraulically-actuated arms, a bucket, and a lifting mechanism. It is used to:
Load materials (earth, gravel, sand, debris) into trucks or bins
Move materials over short distances (less than 100 metres)
Grade and spread materials
Rip and push materials
Load the hopper of a concrete mixer or crusher
2.2 Loader Geometry and Bucket Kinematics
The loader geometry determines its ability to fill the bucket and dump it properly. The critical parameters are:
Parameter
Definition
Operational Impact
Dump angle
Maximum forward angle of the bucket
Must be ≥ 45° for complete dumping
Rollback angle
Maximum rearward angle of the bucket
Must be ≥ 40° to retain the load
Lift height
Maximum vertical distance of the bucket pivot point
Determines the dumping height
Reach at maximum height
Horizontal distance of the bucket at maximum height
Critical for truck loading
Digging depth
Maximum depth below ground level
Limits use in light excavation
Parallel kinematics principle: Loader arms are designed to maintain the bucket at a relatively constant angle during lifting. This prevents spillage and allows for uniform loading. The leveling cylinder automatically compensates for arm rotation.
2.3 Forces at Play and Stability
Loader stability is governed by three main factors:
20.Centre of gravity (CG): Positioned between the axles when the loader is empty. The CG moves forward and upward when the bucket is loaded and raised.
21.Tipping line: An imaginary line passing through the contact points of the front wheels with the ground. If the vertically projected CG extends beyond this line, the equipment tips forward.
22.Overturning moment: The product of the load mass and the horizontal distance between the load's CG and the tipping axis.
Stability formula:
Overturning moment = Load mass × Horizontal distance to the tipping point
For a quick calculation of safe lifting capacity:
Net capacity = (Equipment mass × Distance from CG to rear axle) ÷ Distance from bucket to front axle
Rule of thumb: The loader's rated capacity (ROPS/FOPS) is indicated on the manufacturer's plate. This capacity is based on a material of average density (1,600 kg/m³). For denser materials, the actual capacity must be reduced proportionally.
3. Loading and Operating Techniques
3.1 Complete Loading Cycle
The efficient loading cycle comprises five distinct phases:
32.Approach: The equipment approaches the material pile at a right angle, in a straight line, at reduced speed (1st or 2nd gear).
33.Penetration: The bucket is positioned horizontally, slightly tilted downward (2° to 5°), and pushed into the material. The approach speed must be constant and controlled.
34.Filling: Once the bucket is embedded to about 2/3 of its depth, slightly raise the arms (10° to 15°) and roll back the bucket to fill it completely. This combined action creates a "rolling" effect that maximizes filling.
35.Retraction and travel: The loaded bucket is fully rolled back, the arms are raised to travel height (30 to 50 cm from the ground), and the equipment reverses or advances toward the dumping point.
36.Dumping: The bucket is raised to the required height, then emptied by tilting forward. For a truck, dumping should occur at approximately 15 cm above the side wall of the box.
3.2 Bucket Filling Techniques
Full bucket method:
Penetrate the pile with the bucket flat
Raise the arms and roll back the bucket simultaneously
Use the machine's momentum to push through the material
Never lift the rear wheels off the ground
Partial bucket method:
Penetrate the pile with the bucket tilted downward
Roll back the bucket progressively
Use for very dense or cohesive materials (clay, wet earth)
Factors affecting filling:
Factor
Effect
Correction
Dry, loose material
Easy filling but possible spillage
Reduce penetration speed
Wet, sticky material
Adhesion to bucket, difficult dumping
Use a smooth-walled bucket, reduce the load
Frozen or compacted material
Difficult penetration
Use the "shearing" technique (penetrate in successive layers)
Large rocks
Risk of overload and damage
Pre-select rocks, use a toothed bucket
3.3 Truck Loading
Optimal positioning: The truck should be positioned at a 45° angle to the material pile. The loader works between the pile and the truck, minimizing travel distances.
Dumping height: The loader's dumping height must be at least 30 cm higher than the truck's side wall height. Check the manufacturer's specifications for maximum dumping height at full lift.
Loading procedure:
53.Approach the truck with the loaded bucket at travel height
54.Raise the bucket to dumping height before reaching the truck
55.Position the bucket over the centre of the box
56.Tilt the bucket to dump the material
57.Shake the bucket slightly (2-3 oscillations) to empty it completely
58.Reverse and lower the bucket to travel height
Load distribution: For a three-axle truck, the load should be distributed as follows: 25% on the front axle, 50% on the rear tandem, 25% in the centre. For a two-axle truck: 50% front, 50% rear.
3.4 Grading and Spreading
Grading technique:
Use the bucket slightly tilted rearward (cutting angle of 5° to 10°)
Work in reverse for precise grading
Make successive passes with a 1/3 bucket-width overlap
Maintain a constant, slow speed (2 to 4 km/h)
Material spreading:
Dump material in layers 15 to 20 cm thick
Use the bottom of the bucket to smooth the surface
Compact each layer before adding the next (if required by the specifications)
4. Calculations and Capacities
4.1 Hourly Production Calculation
The hourly production of a loader is calculated as follows:
Production (m³/h) = (Bucket capacity × Fill factor × 60) ÷ Cycle time (minutes)
Actual efficiency: Multiply by the efficiency factor (50 min/h = 0.83; 45 min/h = 0.75). For continuous work with breaks: 0.83 × 122.7 = 101.8 m³/h.
4.2 Volume and Mass Conversions
Essential formulas:
Mass (kg) = Volume (m³) × Density (kg/m³)
Bank volume (BV): volume in its natural state
Loose volume (LV): volume after excavation (swell)
Compacted volume (CV): volume after compaction
Swell and compaction factors:
Material
Bank density (kg/m³)
Swell (%)
Loose density (kg/m³)
Sand
1,800
10 – 15
1,600
Gravel
2,000
12 – 18
1,700
Clay
2,000
25 – 35
1,500
Topsoil
1,600
20 – 30
1,250
Rock (limestone)
2,600
40 – 60
1,700
Example: Excavating 100 m³ of bank clay. The loose volume will be 100 × 1.30 = 130 m³. The number of truck trips (10 m³ capacity) = 130 ÷ 10 = 13 trips.
4.3 Lifting Capacity and Load Moment
Net capacity formula:
Net capacity = (Equipment mass × Distance from CG to front axle) ÷ (Distance from bucket to front axle)
Example:
Equipment mass: 8,000 kg
Distance CG to front axle: 1.2 m
Distance bucket to front axle: 2.5 m
Net capacity = (8,000 × 1.2) ÷ 2.5 = 3,840 kg
Verification with material: For gravel (1,700 kg/m³), the maximum volume in a 1.0 m³ bucket is 3,840 ÷ 1,700 = 2.26 m³. The 1.0 m³ bucket can therefore be filled to full capacity without risk of tipping.
Safety rule: Never exceed 75% of the tipping load for lifting operations. For normal loading operations, never exceed 50% of the tipping load.
5. Safety and Regulations
5.1 Applicable Canadian Standards
Loader operations are governed by several national standards:
Standard
Application
CSA B352.0
Roles and responsibilities of mobile equipment operators
CSA B354.1
Safety requirements for elevating work platforms
CSA Z96
High-visibility safety clothing
CSA Z462
Electrical safety (overhead power lines)
Canada Labour Code, Part II
Occupational health and safety (federal jurisdiction)
Rule 8-200 of the Canadian Electrical Code, Part I (CE Code): This rule requires a minimum distance of 3 metres between any mobile equipment and overhead power lines of less than 75 kV, and 5 metres for lines over 75 kV. For lines of 250 kV and above, the distance must be calculated using the formula: Distance (m) = 0.3 + 0.01 × Voltage (kV).
117.ROPS/FOPS structure: No cracks, deformations, or corrosion
Hydraulic system inspection procedure:
Check system pressure with the gauge (typical pressure: 150 to 200 bars)
Check oil temperature (operating temperature: 50°C to 80°C)
Inspect hydraulic filters (replace according to manufacturer's interval)
Check for air bubbles in the reservoir (indication of air intake)
5.3 Danger Zones and Communication
Loader danger zone: 3-metre radius around the equipment, extended to 5 metres during loading operations. This zone must be delineated with cones or barriers.
Communication with ground workers:
Use a flagman for reversing operations
Establish a hand signal code before starting work
Never move the equipment if the flagman is not visible
Use a radio system if the distance exceeds 50 metres
Standardized hand signals:
Signal
Meaning
Arm raised, open palm
Stop
Arm raised, index finger pointing up
Raise the bucket
Arm raised, index finger pointing down
Lower the bucket
Circular motion of the fist
Move forward
Circular motion of the fist toward the rear
Move backward
Both hands on head
Operation complete
6. Maintenance and Troubleshooting
6.1 Preventive Maintenance of the Loader
Typical maintenance intervals:
Interval
Operation
Every shift
Check fluid levels, grease pivot points
50 hours
Complete greasing, hose inspection
250 hours
Replace hydraulic filter, inspect bucket teeth
500 hours
Replace hydraulic oil, inspect bearings
1,000 hours
Replace fuel and air filters, complete inspection
Loader grease points:
Arm articulations (4 points)
Lift cylinders (2 points)
Leveling cylinder (2 points)
Bucket pivot (2 points)
Leveling mechanism articulations (4 points)
Grease type: NLGI #2 lithium grease for general applications. For cold climates (temperatures below -20°C), use NLGI #0 or #00 grease.
6.2 Common Troubleshooting
Symptom
Probable cause
Solution
Bucket won't lift
Low hydraulic oil level
Check and top up the level
Bucket won't lift
Clogged hydraulic filter
Replace the filter
Bucket won't lift
Faulty hydraulic pump
Test pressure, replace the pump
Bucket lowers by itself
Leaking lift cylinder
Replace cylinder seals
Bucket won't dump completely
Insufficient dump angle
Check geometry, adjust stops
Vibrations in the hydraulic system
Air in the circuit
Bleed the hydraulic circuit
Hydraulic system overheating
Contaminated or low oil
Drain and replace the oil
Hydraulic circuit bleeding procedure:
147.Start the engine and let it idle
148.Actuate each hydraulic function (lift, tilt, attachments) 5 to 10 times
149.Check the oil level and top up if necessary
150.Repeat the operation until movement is smooth and jerk-free
Consumption estimate: A typical tractor-loader-backhoe consumes 8 to 15 litres of diesel fuel per hour, depending on conditions. Specific consumption is approximately 0.25 L/kWh.
7.2 Environmental Protection
Spill management:
Carry a spill kit on board (absorbents, barriers)
Report any fuel or oil spill to the supervisor
Never wash equipment near a watercourse or storm drain
Dust control:
Water travel paths
Reduce travel speed
Use tarps on truck loads
8. Pitfalls to Avoid
182.Confusing bucket capacity with actual capacity: The bucket's rated capacity is based on a standard-density material. For dense materials (rock, ore), the actual load may exceed the machine's lifting capacity.
183.Neglecting the swell factor: Calculating the number of truck trips based on bank volume instead of loose volume. A 100 m³ bank volume can represent 130 m³ loose volume for clay.
184.Forgetting to check for power lines: The minimum 3-metre distance applies to lines under 75 kV. For high-voltage lines, the distance increases considerably.
185.Overloading the bucket to "save time": This practice increases the risk of tipping and reduces the service life of hydraulic components.
186.Using the loader as an excavator: The loader is not designed for deep digging. Using the loader for excavation below ground level damages the arms and frame.
187.Ignoring signs of hydraulic hose wear: A damaged hose can burst under pressure, spraying hot oil and causing serious injury.
188.Working with the bucket raised: Traveling with the bucket in the raised position reduces stability and visibility. Always travel with the bucket 30-50 cm from the ground.
190.Confusing hand signals: A misinterpreted signal can cause an accident. Always confirm signals before starting work.
191.Forgetting the parking brake: On a slope, equipment without the parking brake engaged can move and cause damage or injury.
9. Summary
The loader is a versatile piece of equipment used for loading, moving, grading, and spreading materials.
Stability depends on the centre of gravity, the tipping line, and the overturning moment. Never exceed 50% of the tipping load for normal operations.
The loading cycle comprises five phases: approach, penetration, filling, retraction, and dumping.
Hourly production is calculated using the formula: (Bucket capacity × Fill factor × 60) ÷ Cycle time.
Swell factors range from 10% (sand) to 60% (rock). Always use loose volume to calculate transport requirements.
CSA B352.0 standards and the Canadian Electrical Code, Part I (CE Code), Chapter V (Rule 8-200) define safety requirements.
Daily inspection is mandatory and must cover fluids, the hydraulic system, the bucket, tires, brakes, and safety devices.
Preventive maintenance follows fixed intervals (50, 250, 500, 1,000 hours) and includes greasing, filter replacement, and component inspection.
The danger zone around the loader is 3 metres (5 metres during loading). Communication with ground workers must be established before starting work.
Fuel efficiency depends on engine speed, loading technique, and tire pressure.
10. Review Questions
206.Calculate the hourly production of a loader with a 1.2 m³ bucket loading dry sand (factor 0.95) with a cycle time of 0.5 minutes and an efficiency of 50 min/h.
207.A 10 m³ truck must transport 150 m³ of bank topsoil (25% swell). How many trips are required?
208.What is the minimum distance to maintain between the loader and a 120 kV power line?
209.What are the five main loader grease points and at what interval should they be greased?
210.Describe the hydraulic circuit bleeding procedure.
211.A 1.0 m³ bucket is filled with crushed rock (loose density 1,700 kg/m³). The net lifting capacity is 3,500 kg. Can the bucket be filled to full capacity?
