Earthmoving Equipment Operations

Earthmoving Equipment Operations

Richard Skiba

Copyright © 2024 by Richard Skiba

All rights reserved.

No portion of this book may be reproduced in any form without written permission from the publisher or author, except as permitted by copyright law.

This publication is designed to provide accurate and authoritative information in regard to the subject matter covered. While the publisher and author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives or written sales materials. The advice and strategies contained herein may not be suitable for your situation. You should consult with a professional when appropriate. Neither the publisher nor the author shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, personal, or other damages.

Skiba, Richard (author)

Earthmoving Equipment Operations

ISBN 978-1-76350-134-8 (paperback) 978-1-76350-135-5 (eBook) 978-1-76350-136-2 (Hardcover)

Non-fiction

Contents

Preface

1.Introduction

2.Skid Steer Operations

3.Loader Operations

4.Backhoe/Loader Operations

5.Excavator Operations

6.Dozer Operations

7.Water Truck Operations

8.Haul Truck Operations

9.Surfacing Operations

10.Earthmoving in Mining and Civil Construction Work Environments

11.Operator Calculations

References

Preface

This book covers a selective range of earthmoving equipment, specifically skid steers, front end loaders, backhoes, excavators, dozers, water trucks, haul and tip trucks, stabilizers and roller compactors. For each of these, the uses, key components, operating principles, preparation for operations, operational practices, safe operation and finalising operations is covered.

The earthmoving equipment information provided within this book is intended to be general in nature and may not encompass all aspects of its operation. It is important to note that each item of plant or equipment has its own specific characteristics and operational requirements that may vary. Earthmoving equipment operators are strongly advised to consult the manufacturer's guides and manuals prior to the operation of any equipment to ensure compliance with safety standards and operational procedures.

Furthermore, it is crucial to acknowledge that operations and terminology can differ across jurisdictions. Earthmoving equipment operators should be aware that regulations and guidelines pertaining to equipment usage may vary depending on the location. Therefore, it is essential for equipment operators to familiarize themselves with the applicable laws, regulations, and standards in their respective jurisdictions.

Additionally, earthmoving equipment operators are urged to review workplace policies and procedures before operating any equipment. Workplace-specific protocols may exist to address unique hazards and safety considerations, which must be adhered to for safe operations.

Moreover, it is important to recognize that in many jurisdictions, operational licensing requirements apply. Earthmoving equipment operators are responsible for ensuring that they meet all jurisdictional legislative requirements relevant to their sites of practice. This may include obtaining appropriate licenses, certifications, or permits to operate cranes legally and safely within their jurisdiction.

Sample load charts, specifications, interpretations and calculations are used throughout this book for demonstration purposes only and should not be taken to be used in any other manner. Every equipment model is accompanied by its own distinct operational charts and characteristics, which may vary depending on the equipment's configurations and rated capacity and is supplied by the equipment’s manufacturer. They are not portable from one model to another, and operators must always ensure they are referring to documentation relevant to the plant they are operating.

While efforts have been made to provide accurate and informative equipment operation information, users are reminded of the need for due diligence and compliance with applicable regulations, manufacturer guidelines, workplace policies, and licensing requirements to ensure safe and lawful crane operations.

Chapter one

Introduction

Earthmoving equipment refers to a broad category of heavy machinery designed for various tasks related to moving earth, soil, rocks, and other materials during construction, excavation, mining, landscaping, and agricultural activities. These machines are used to manipulate the earth's surface for purposes such as grading, leveling, excavating, digging, and transporting materials. Some common types of earthmoving equipment include bulldozers, excavators, backhoes, wheel loaders, dump trucks, graders, trenchers, and skid steer loaders. Each type of equipment serves specific functions and is essential in different stages of construction and earthmoving projects.

Earthmoving encompasses the process of relocating large volumes of soil using heavy machinery, typically employed for excavating building foundations and transporting materials to and from construction sites.

Additionally, earthmoving equipment plays a crucial role in clearing debris, vegetation, and obstacles from designated areas. Its applications extend to excavating trenches, facilitating mining operations, and ensuring proper grading.

Furthermore, this equipment is indispensable for prepping land for various projects, including residential developments, civil engineering endeavours such as road construction, drainage systems, bridges, and parking facilities, among others. Essentially, earthmoving serves as the backbone of infrastructure and construction initiatives.

A diverse array of earthmoving machinery exists, ranging from compact units tailored for confined spaces to industrial-grade behemoths found in extensive mining and quarry operations. These machines may utilize steel or rubber tracks or heavy-duty tyres, depending on their intended use.

Each piece of earthmoving machinery is purpose-built, with some models designed for excavation and soil relocation, others for material transport, and yet others for compaction tasks. Specialized equipment is available for grading, creating inclines, trenching, and various ground-cutting operations. Moreover, versatile machinery is capable of multifunctionality, catering to a wide range of earthmoving requirements.

While the range of earth-moving equipment is extensive, encompassing everyday vehicles to specialized machinery, let's focus on the primary types commonly used today:

Excavator: Among the most prevalent and indispensable pieces of equipment on construction sites, the excavator is designed for excavation tasks. Comprising components like tracks/wheels, a cab, boom, stick, hydraulic arm, and attachment (usually a metal bucket or scoop), it efficiently removes soil and rocks from one location and deposits them elsewhere. Besides excavation, it performs diverse tasks such as material mixing, site cleaning, pipe laying, demolition, landscaping, trench digging, and more.

Figure 1: A Caterpillar 330 excavator scooping up dirt. Matthew T Rader, CC BY-SA 4.0, via Wikimedia Commons.

Wheel Loader: Crucial for moving heavy materials within construction sites, the wheel loader features a large front bucket or scoop for transporting dirt, rocks, or other materials. Equipped with four large wheels, a cab, booms, hydraulic arm, and a sizable metal bucket, it facilitates tasks like material transportation, loading into other vehicles, backfilling, site cleaning, and lifting.

Figure 2: Komatsu WA150 front end loader. Bob Adams from Amanzimtoti, South Africa, CC BY-SA 2.0 , via Wikimedia Commons.

Backhoe Loader: Combining excavation and loading capabilities, the backhoe loader is versatile, featuring a front bucket for loading and a rear-mounted bucket for excavation. Its adaptability is enhanced by the option to replace buckets and loaders with various attachments. Apart from loading and excavation, it can be used for landscaping, material mixing, benching, lifting, trenching, and more.

Figure 3: Case 580 Super N backhoe loader. Daderot, CC0, via Wikimedia Commons.lly generated

Dozer: A heavy-duty machine capable of pushing vast amounts of dirt and rock with its front-mounted blade, the dozer is essential for leveling, drain cutting, and other tasks requiring significant pushing force. It often features a rear-mounted ripper for breaking harder materials. Modern advancements include programmable controls for precision grading.

Figure 4: Komatsu bulldozer pushing coal. Petar Milošević, CC BY-SA 4.0, via Wikimedia Commons.

Skid Steer Loader / Track Loader: Compact, agile, and highly versatile, the skid steer loader is ideal for manoeuvring in tight spaces. Its front attachment can be swapped for various options like a bucket, rotary hoe, dozer blade, hammer, or auger, making it adaptable for tasks such as rock breaking, site cleanup, loading, excavating, and more.

Figure 5: Mustang 2054 skid-steer loader. Orderinchaos, CC BY-SA 4.0 , via Wikimedia Commons.

Dump Trucks: Essential for transporting large quantities of materials within construction sites, dump trucks efficiently move material from one location to another before depositing it at the final destination.

Figure 6: Dump truck. Noorse, CC BY 2.0, via Wikimedia Commons.

Trenchers: Primarily used for digging trenches, trenchers employ a conveyor system to excavate and deposit dirt alongside the trench.

Figure 7: Eagle 6500 wheel trencher. Trencher Expert, CC BY-SA 3.0, via Wikimedia Commons.

Scrapers: Designed for swift movement of dirt across large areas, scrapers excel in digging and leveling tasks on expansive construction sites.

Figure 8: Caterpillar 613C Scraper. Bill Jacobus from Houston, USA, CC BY 2.0, via Wikimedia Commons.

The operational principles of earthmoving equipment vary depending on the type of equipment but generally include the following key aspects:

Power Source: Earthmoving equipment is powered by various sources such as diesel engines, electric motors, or hydraulic systems. The power source provides the energy required to operate the equipment's components.

Control Systems: Earthmoving equipment is equipped with control systems that enable operators to manage the movement and functions of the machinery. These control systems may include joysticks, levers, pedals, or electronic interfaces.

Hydraulic Systems: Many types of earthmoving equipment utilize hydraulic systems to generate power and control movements. Hydraulic fluid is pressurized by a pump and then directed to hydraulic cylinders, motors, or other actuators to move components like booms, buckets, or blades.

Mechanical Components: Earthmoving equipment comprises various mechanical components such as tracks, wheels, gears, and bearings. These components facilitate movement, stability, and functionality of the machinery.

Attachments: Most earthmoving equipment can be equipped with different attachments to perform specific tasks. For example, excavators may use buckets, augers, or hammers, while bulldozers may use blades or rippers. The attachment is often interchangeable to suit different job requirements.

Safety Features: Safety is a paramount concern in the operation of earthmoving equipment. Equipment is designed with safety features such as rollover protection structures (ROPS), falling object protection systems (FOPS), backup alarms, and emergency stop mechanisms to protect operators and bystanders.

Maintenance Requirements: Regular maintenance is essential to ensure the proper functioning and longevity of earthmoving equipment. Maintenance tasks may include lubrication, inspection of components, replacement of worn parts, and troubleshooting of mechanical or hydraulic issues.

Operator Training: Proper training is necessary for operators to understand the operational principles, safety procedures, and maintenance requirements of earthmoving equipment. Training programs educate operators on equipment controls, techniques for efficient operation, and protocols for safe working practices.

Overall, the operational principles of earthmoving equipment involve the effective utilization of power sources, control systems, hydraulic mechanisms, mechanical components, attachments, safety features, maintenance practices, and operator training to accomplish various construction and excavation tasks efficiently and safely.

Earthmoving equipment operators need to possess a range of knowledge and skills to operate machinery safely and effectively. These include:

Equipment Familiarity: Operators should have a thorough understanding of the specific earthmoving equipment they will be operating, including its controls, functions, capabilities, and limitations. This includes knowing how to start and shut down the equipment properly.

Safety Procedures: Safety is paramount in the operation of earthmoving equipment. Operators need to be aware of safety protocols and procedures, including the proper use of personal protective equipment (PPE), adherence to site safety regulations, and precautions to prevent accidents, such as rollovers, collisions, or equipment malfunctions.

Site Conditions: Operators should assess site conditions before starting work, including terrain, ground stability, obstacles, and overhead hazards. Understanding the site environment helps operators anticipate potential risks and adapt their operating techniques accordingly.

Operating Techniques: Effective operation of earthmoving equipment requires skill and precision. Operators need to learn proper operating techniques for tasks such as digging, lifting, grading, pushing, and loading. This includes controlling equipment speed, direction, and attachments to achieve desired results efficiently.

Maintenance Awareness: Operators should be aware of basic equipment maintenance practices to ensure machinery remains in optimal working condition. This includes conducting pre-operation inspections, checking fluid levels, greasing moving parts, and reporting any mechanical issues or abnormalities.

Communication Skills: Clear communication is essential for safe and efficient operation, especially when working in teams or with ground personnel. Operators should be able to communicate effectively using hand signals, two-way radios, or other communication devices to coordinate movements, signal warnings, and convey instructions.

Emergency Procedures: Operators should be familiar with emergency procedures and know how to respond quickly and appropriately in case of accidents, equipment malfunctions, or other emergencies. This includes knowing how to shut down equipment, evacuate the area safely, and administer first aid if necessary.

Environmental Considerations: Operators should be mindful of environmental factors such as weather conditions, environmental regulations, and potential impacts on surrounding ecosystems. Minimizing environmental damage and ensuring compliance with regulations are important aspects of responsible equipment operation.

Regulatory Compliance: Operators should be aware of relevant regulations and standards governing equipment operation, including licensing requirements, load limits, noise restrictions, and emissions standards. Compliance with these regulations helps ensure safe and legal operation of earthmoving equipment.

By acquiring knowledge and skills in these areas, earthmoving equipment operators can perform their duties safely, efficiently, and responsibly, contributing to successful construction and excavation projects while minimizing risks to personnel and the environment.

Frequently, earthmoving machinery finds application in projects centred around land preparation and laying foundations, typically marking the outset of larger-scale endeavours.

Nevertheless, earthmoving equipment proves invaluable across a spectrum of projects, encompassing mining operations, aggregate quarries, bridge and tunnel construction, site clearance, reservoir and dam development, road and railway infrastructure, municipal constructions, as well as the installation of sewers and underground pipe networks.

The remaining chapters of this book cover the safe operating principles and applications of the following earthmoving equipment:

Skid Steer Operations

Loader Operations

Backhoe/Loader Operations

Excavator Operations

Dozer Operations

Water Truck Operations

Haul Truck Operations

Surfacing Operations

There are various reasons why individuals may be drawn to a career as an earthmoving equipment operator. Operating heavy machinery offers a hands-on and dynamic work environment. For those who thrive on physical engagement and enjoy working with their hands, the role of an earthmoving equipment operator can be highly appealing.

Earthmoving equipment operators have the opportunity to work with a diverse range of machinery, including excavators, bulldozers, loaders, graders, and more. This diversity keeps the job stimulating and allows operators to cultivate skills across various types of equipment.

The construction and mining industries, where earthmoving equipment is integral, often provide stable employment prospects. With ongoing demand for infrastructure projects and mining operations, there remains a consistent need for skilled equipment operators.

Earthmoving equipment operators typically receive competitive compensation, particularly as they accrue experience and proficiency in operating different types of machinery. Additionally, opportunities for overtime pay and benefits may be available, depending on the employer.

As at March 2024, in the United States, excavator operators earn an average hourly wage of $24.85 (USD), equivalent to $57,950 annually, with salaries ranging from $41,193 to $81,525. In Australia, the average annual salary for excavator operator positions falls between $130,000 and $150,000 (AUD). Meanwhile, in the United Kingdom, the typical wage for excavator operators is £19.35 per hour or £36,369 annually (GBP), and in Canada, it averages $62,098 per year (CAD) (Indeed, 2024b; Seek, 2024; Seek UK, 2024b; talent.com, 2024).

In Australia, the average annual salary for Dump Truck Operator positions spans from $115,000 to $135,000, with a median salary of $95,693 per year and a salary range of $92,000 to $124,000 for haul truck drivers. Meanwhile, in the United Kingdom, dumper drivers receive an annual median salary of £31,200 or £16 per hour, averaging £17.69 (Glassdoor, 2024; Indeed, 2024b; Seek UK, 2024b).

Backhoe operator salary in United States is $23.81 hourly, or $55,593 annually, with a range from $37,743 to $81,885. In UK, on average backhoe operators are paid £32,886 annually (Indeed, 2024a; Seek UK, 2024a).

Through accumulated experience and additional training, earthmoving equipment operators can progress in their careers and assume roles with greater responsibilities. These roles may include equipment supervisor, site manager, or safety coordinator, offering avenues for professional growth and development.

Many earthmoving equipment operators appreciate the opportunity to work outdoors, often in diverse settings such as construction sites, mining operations, and infrastructure projects. This outdoor work environment provides a refreshing change of scenery and allows individuals to connect with nature while working.

Earthmoving equipment operators play a pivotal role in construction and development endeavours, contributing to the creation of roads, bridges, buildings, and other vital infrastructure. Knowing that their work is fundamental to shaping the built environment can be deeply fulfilling for operators.

Pursuing a career as an earthmoving equipment operator can be an enticing choice for individuals seeking hands-on work, job stability, competitive wages, and the chance to make a meaningful impact in construction and development projects.

Chapter two

Skid Steer Operations

Askid loader, also known as a skid-steer loader or skidsteer, is a compact, engine-powered machine featuring a rigid frame and lift arms designed to accommodate various labour-saving tools or attachments. Numerous manufacturers produce their own versions of this equipment, including Kubota, Bobcat, Terex, Case, Caterpillar, Gehl Company, Hyundai, JCB, JLG, John Deere, Komatsu, LiuGong, New Holland, Volvo, Wacker Neuson, among others.

Skid-steer loaders are versatile machines used across a wide range of industries and applications due to their compact size, manoeuvrability, and ability to accommodate various attachments. Some common uses of skid-steer loaders include:

Construction: Skid-steer loaders are extensively used in construction sites for tasks such as digging, grading, trenching, and material handling. They can manoeuvre easily in tight spaces, making them ideal for tasks in confined areas.

Landscaping: Landscapers utilize skid-steer loaders for tasks such as grading, leveling, excavation, and moving materials like soil, mulch, and gravel. They are also used for tasks like tree removal, stump grinding, and brush clearing.

Agriculture: Farmers and ranchers use skid-steer loaders for various agricultural tasks, including feeding livestock, cleaning barns, moving hay bales, and maintaining fences. They are also used for tasks like planting, tilling, and harvesting in smaller-scale operations.

Snow Removal: Skid-steer loaders equipped with snowblower or snow plow attachments are commonly used for snow removal in parking lots, driveways, sidewalks, and other areas where larger vehicles may not be suitable.

Demolition: Skid-steer loaders are used in demolition projects for tasks such as breaking down structures, removing debris, and clearing sites. Their compact size allows them to work efficiently in confined spaces and navigate around obstacles.

Utility Work: Skid-steer loaders are used by utility companies for tasks such as digging trenches for laying pipes and cables, repairing utility lines, and general maintenance of infrastructure.

Forestry: In forestry operations, skid-steer loaders are used for tasks such as clearing brush, removing tree stumps, and transporting logs. They are often equipped with forestry-specific attachments for these tasks.

Waste Management: Skid-steer loaders are used in waste management facilities for tasks such as loading and unloading dumpsters, sorting recyclables, and managing landfill operations.

General Maintenance: Skid-steer loaders are valuable for general maintenance tasks in various settings, including parks, golf courses, campuses, and industrial facilities. They can be used for tasks such as cleaning, landscaping, and light construction work.

Overall, skid-steer loaders offer versatility and efficiency, making them valuable assets in a wide range of industries and applications.

Skid-steer loaders typically feature four-wheel configurations, with wheels mechanically locked in synchronization on each side. The left-side drive wheels can operate independently from the right-side drive wheels, with no separate steering mechanism. Instead, the machine turns by varying the speed of the wheel pairs, causing the vehicle to skid or drag its fixed-orientation wheels across the ground. The robust frame and durable wheel bearings prevent damage from the torsional forces generated by this skidding motion. Steering is achieved by generating differential velocity at opposing sides of the vehicle.

Figure 9: Mustang 2054 skid-steer loader. Orderinchaos, CC BY-SA 4.0, via Wikimedia Commons.

Similar to tracked vehicles, skid steers can cause significant friction on soft or fragile surfaces, potentially damaging them. However, this can be mitigated by using specialized wheels like the Mecanum wheel, which reduces ground friction. Skid-steer loaders excel in manoeuvrability, capable of executing zero-radius turns, making them valuable for compact and agile loading tasks. Some skid-steer loaders can be fitted with tracks instead of wheels, known as multi-terrain loaders.

In contrast to a traditional front loader, the lift arms of these machines run parallel to the operator, with the pivot points positioned behind the driver's shoulders. Due to the operator's close proximity to moving parts, early skid loaders posed safety concerns compared to conventional front loaders, especially during operator ingress and egress. However, modern skid loaders are equipped with fully enclosed cabs and additional safety features to safeguard the operator. Similar to conventional front loaders, they can move materials between locations, transport materials in their buckets, and load materials onto trucks or trailers.

Figure 10: Components of a Skid Steer. Back image - Bobcat S650 skid steer loader, Bob Adams from George, South Africa, CC BY-SA 2.0, via Wikimedia Commons.

A skid steer loader serves as a versatile machine utilized for excavating, gathering, lifting, and relocating various materials, notably dirt and sand. Additionally, it performs tasks such as grading, jackhammering cement, and loading trucks. Popular activities involving skid steers encompass site cleanup, material spreading, road sweeping, backfilling, loading and removing materials, turf preparation, and slab preparation, among others.

Predominantly employed for excavation purposes, the skid steer boasts versatility, agility, and lightness, with an array of attachments available for diverse applications. It is commonly found in construction sites, where its adaptable arms accommodate various landscaping functions.

In Australia, these machines are often referred to as bobcats, though in countries like America, this term specifically refers to a prominent skid steer brand that gained popularity in the 1970s, remaining one of the largest skid steer brands globally.

Another variant, multi-terrain loaders, comes into play when ground conditions necessitate enhanced traction, such as in snow, mud, sand, or bush. Skid steers feature steering locked on both sides, allowing independent operation of the right and left wheels or tracks. This configuration enables the skid steer to achieve exceptional manoeuvrability and execute sharp turns, known colloquially as turning on a dime.

Typically, the loader arms operate via hydraulics, enabling the bucket or other attachments to lift either vertically or radially. Radial movement allows the bucket to arc away from the skid steer until reaching heights as high as the cab before retracting inward.

When considering skid steer hire options, choices typically include two-track skid steer hire or four-wheel skid steer hire. In terms of operation, the wheels can be independently operated on either side of the machine, with the front and back axles synchronized. As the wheels maintain a fixed straight alignment and lack the ability to turn, the skid steer operator must increase the speed of the wheels on one side to induce dragging or skidding across the surface. This action prompts the machine to rotate in the opposite direction, hence the name skid steer.

Skid steer hire is exceedingly popular across construction, landscaping, and mining industries due to its versatile nature. Whether opting for a two-track or four-wheel skid steer hire, understanding the variety of attachment options available is crucial for optimizing project outcomes. Among the most common attachments when hiring a skid steer is a bucket, though a wide range of alternatives exists to facilitate various tasks. These may include stump grinder hire, tree spade hire, wood chipper hire, trench-digging hire, pallet fork hire, bale spear hire, ripper hire, tiller hire, trencher hire, wheel saw hire, pavement miller hire, and cement mixer hire, among others.

Ultimately, skid steer hire offers a multitude of benefits across diverse applications, enabling the completion of tasks that singular plant hire options may not accomplish. Prior to hiring a machine, understanding the potential advantages for budget and project timelines is crucial. Whether undertaking landscaping, excavation, construction, or snow-clearing tasks, skid steer hire presents an efficient and reliable solution, provided the machine is well-maintained, properly serviced, and operated by licensed professionals.

Figure 11: Tracked skid steer. Wikideas1, CC0, via Wikimedia Commons.

There are different types of skid steers, each designed with specific features to suit various applications. These include:

Wheeled Skid Steers:

Wheeled skid steers are equipped with rubber tyres, making them suitable for use on solid surfaces like pavement, concrete, and hard-packed soil.

They offer excellent manoeuvrability and speed, making them ideal for tasks that require frequent relocation or travel over short distances.

Wheeled skid steers are commonly used in construction, landscaping, agriculture, and material handling operations.

Tracked Skid Steers:

Tracked skid steers, also known as compact track loaders (CTLs), feature tracks instead of wheels, providing better traction and flotation, especially on soft or uneven terrain.

These machines are well-suited for operations in muddy, sandy, or rough terrain where wheeled skid steers may struggle.

Tracked skid steers exert lower ground pressure, reducing soil compaction and minimizing damage to delicate surfaces.

They are commonly used in forestry, landscaping, agriculture, and construction applications where terrain conditions are challenging.

Mini Skid Steers:

Mini skid steers are compact versions of standard skid steers, designed for applications that require manoeuvrability in confined spaces or where access is limited.

These machines are smaller in size and lighter in weight compared to conventional skid steers, making them suitable for use in residential areas, urban environments, and indoor spaces.

Mini skid steers are often used by landscapers, utility contractors, and homeowners for tasks such as digging trenches, moving materials, and performing light construction work.

Stand-On Skid Steers:

Stand-on skid steers are designed for operators to stand on a platform rather than sit in a traditional cab.

These compact machines offer a smaller footprint and increased visibility, allowing operators to manoeuvre easily in tight spaces and navigate obstacles more effectively.

Stand-on skid steers are commonly used in landscaping, grounds maintenance, and construction applications where manoeuvrability and efficiency are essential.

Each type of skid steer has its advantages and is suited to different applications based on factors such as terrain, space constraints, and specific job requirements. Choosing the right type of skid steer ensures optimal performance and productivity in various working conditions.

Figure 12: Mini/Stand-on skid steer. Ditch Witch SK 1050, Daderot, CC0, via Wikimedia Commons.

Machine Characteristics

The ratio between tread width and wheelbase is crucial for the efficient operation of a skid steer. If the tyres are positioned too far apart, the skid steer will expend excessive power during turns, leading to faster tyre wear. Typically, the recommended tread width to wheelbase ratio is 1.3 to 1 (Goulet & Anderson, 2007).

Tread width refers to the distance measured from the centre of the left tyre to the centre of the right tyre. Wheel base is measured from the centre of the front tyre to the centre of the rear tyre, see .

Figure 13: Tread width and Wheel base. Back image - Bobcat S570 Skid-Steer Loader, Steven Pavlov, CC BY-SA 4.0, via Wikimedia Commons.

As per the guidelines set by the Society of Automotive Engineers (SAE), the rated operating capacity is determined to be half of the tipping load. This rating indicates the maximum weight the machine can safely carry during typical operational circumstances. For instance, if the tipping load is 1996 kg (4400 lb), then the rated operating capacity would be 998 kg (2200 lb), as per the SAE standards (Goulet & Anderson, 2007).

Operators must ensure not to surpass the rated operating capacity, as doing so can compromise the stability and manoeuvrability of the skid steer, potentially resulting in damage to the equipment. Overloading the bucket or using a heavy attachment in a raised position can cause the skid steer to tip forward. In such instances, failure to utilize the seat restraint may lead to the operator being ejected from the protective cab. This can result in the skid steer running over the operator or causing the operator to be crushed by the bucket or load.

The weight distribution of a skid steer is intentionally unequal between the front and rear wheels, typically set at a ratio of 70% to 30%. This configuration enhances the skid steer's manoeuvrability, particularly when turning. If the weight distribution were to be evenly split between the front and rear wheels, at 50% each, the skid steer would require more engine power and would experience diminished turning capabilities. When the bucket is empty, approximately 70% of the weight rests on the rear wheels, with the remaining 30% on the front wheels (Goulet & Anderson, 2007). Conversely, when the bucket is full, the weight distribution shifts, with around 70% of the weight now borne by the front wheels and 30% by the rear wheels. Refer to Figure 14

Figure 14: Weight on front and rear wheels loaded and empty.

As an example, A skid steer with a total weight of 2806kg (6185lb) and a rated operating capacity of 794kg (1750lb) will have a weight distribution as shown in Figure 15.

Figure 15: Weight distribution calculations.

The tyres bearing 70% of the weight are the ones upon which the machine pivots during operation. Understanding this dynamic is crucial, especially in tight or crowded spaces. When combined with an understanding of the centre of gravity, this knowledge empowers operators to work safely and efficiently.

The centre of gravity (COG) in a skid steer refers to the point where the majority of its weight is concentrated. It's a crucial concept to understand because it affects the stability and balance of the machine during operation.

In a skid steer, the centre of gravity typically lies somewhere within the chassis, often closer to the rear due to the heavy engine and transmission components. However, the exact location can vary depending on factors such as the weight distribution of attachments, load in the bucket, and the position of the operator.

The centre of gravity represents the equilibrium point of a skid steer, where all forces acting on the machine are evenly balanced, see Figure 16. This point shifts continuously during operation, particularly in response to changes in the weight distribution at the front of the skid steer.

Figure 16: Skid steer centre of gravity.

When the skid steer is stationary on level ground, the centre of gravity is usually positioned low and centred between the four wheels. This configuration maximizes stability, making it less likely for the machine to tip over.

During operation, movements such as turning, lifting, or carrying loads can shift the centre of gravity. For example, when turning sharply or lifting a heavy load high off the ground, the centre of gravity moves towards the outside of the turn or the lifted load, respectively. These shifts can affect the stability of the skid steer and increase the risk of tipping over, especially if the centre of gravity moves beyond the machine's stability limits.

When you load the bucket, the centre of gravity shifts forward. Additionally, the centre of gravity adjusts vertically depending on the height and weight of the bucket. As you lift the bucket, the centre of gravity ascends, and the act of lifting transfers weight to the front wheels. Consequently, the centre of gravity rises with