Brakes for Vehicles in Mines

• Issued: April 2015
• Content last reviewed: April 2015
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Purpose

To assist employers, workers and other workplace parties with understanding the requirements in Regulation 854 (Mines and Mining Plants) under the Occupational Health and Safety Act (OHSA), for the purpose of providing safe and reliable braking systems on motor vehicles.

Objectives

• The brakes for motor vehicles operating in underground or surface mines must be capable of stopping and holding a motor vehicle under full load conditions on all operating grades, slopes or ramps.
• Each vehicle must have a redundancy built into the braking systems so that in the event of a single failure of the service brake system, a safe stop can still be made.
• The motor vehicle must be equipped with a parking brake that is unaffected by loss of pressure caused by loss of oil or contraction due to temperature changes.

Legal requirements

In addition to the general requirements in the OHSA:

Brake system requirements

Sections 119, 119.1, and 119.2 of Regulation 854 (Mines and Mining Plants) under the OHSA cover the important requirements.

Testing, maintenance, inspection and other requirements

Sections 105 and 106 of Regulation 854 (Mines and Mining Plants) under the OHSA cover the important requirements.

Background information

A failure in the service brake system of a motor vehicle operating on a ramp in an underground or surface mine can cause a runaway and serious injury if there is no back-up brake system. Potential brake failures could result in runaways of motor vehicles if the brake systems are not tested during operation.

Acceptable practices

Scope of sections 119, 119.1 and 119.2

These sections apply to "motor vehicles" operating on grades, slopes, or ramps.

Regulation 854 defines a "motor vehicle" as a vehicle propelled by other than muscular power, including an automobile, a caterpillar-tracked vehicle, a truck, a tractor and a motor vehicle running on rails but does not include a locomotive.

There are three large groups of motor vehicles used in underground or surface mines: production, utility and personal. These vehicles differ in mass, speed and design of braking systems.

Grades, slopes or ramps are terms that are commonly understood and used in Regulation 854 and related standards. These terms are generally used to refer to an inclined surface that requires braking performance beyond what would be necessary on a flat surface.

Although subsection 119(2) requires that the brake system on a motor vehicle perform the function of three systems (service brake, emergency brake, and parking brake), this does not mean that motor vehicles require three totally separate braking systems or three separate means of activation. In practice, many motor vehicles have only two means of brake activation. However, it is still necessary to have separate means of demonstrating that the function requirements of each of the three systems have been tested and met.

Motor vehicle brake system test requirements

Regulation 854 requires the following motor vehicle brake system tests.

Subsection 119(10) requires tests for a motor vehicle that has never been used in the mine before, including a prototype motor vehicle that is being tried in a mine for the first time. These initial brake system tests are commonly referred to in the industry as "commissioning tests". Subsection 119(11) contains requirements for the records of these tests:

• Commissioning tests must be performed by a competent person (as defined in the OHSA).
• A record of the commissioning tests must be signed by the competent person who performed the test and must be kept for as long as the motor vehicle is in service.
• A copy of the commissioning tests must be made available to the joint health and safety committee or the health and safety representative, if any.

The manufacturer’s recommendations for testing should be incorporated into any test procedure.

Section 119.1 requires that commissioning tests be performed on specified types of motor vehicles first used in underground or surface mines in Ontario after certain dates, to ensure they meet the relevant CSA and ISO standards dealing with test procedures for brake systems. These subsections require compliance with the standards which set out minimum performance criteria and test procedures to enable uniform assessment of braking systems.

CSA-M3450-03 (for rubber-tired vehicles on surface mines, referred to in subsection 119.1(2)) and ISO 10265 (for tracked motor vehicles on underground and surface mines, referred to in subsection 119.1(3)) standards require a test report for a motor vehicle that is first used in a mine. The mine owner may be able to obtain a copy of the commissioning tests report from the manufacturer or supplier if requested.

Compliance with sections 119(10), 119(11), 105(7)(a) and 106(4)(c) is required even if the mine has a copy of the manufacturer’s commissioning tests report.

The Regulation also requires that a motor vehicle’s brakes be tested prior to initial use for the shift under section 105(7)(a) and before accessing a main ramp in a mine under section 106(4)(c). These requirements may be conducted according to the same procedure required under section 119(10):

• The operator or a competent person should be able to perform pre-shift tests of the service or emergency systems alone, either against the engine or by stopping from a set speed and measuring the stopping distance as recommended by the manufacturer.
• The operator or a competent person should be able to perform pre-shift tests of the parking brake system against the engine or on a slope as recommended by the manufacturer.
• The manufacturer’s recommendations for testing should be incorporated into any pre-shift test procedure.
• Pre-shift test procedures should be posted on the machine or made readily available in a convenient location for access by the operator.

Industry practice

Motor vehicles having a rated gross mass of 7,000 kg or less

Small personnel motor vehicles and light trucks typically use a cable that operates mechanically on the shoes or disks of the rear brakes for an emergency / parking brake system. The cable-operated brakes are considered commonly accepted practice for emergency / parking brakes if all of the other requirements for each of these two systems are met and confirmed by vehicle testing. However, a spring applied hydraulically released (SA/HR) system is offered by some manufacturers.

It is typical for small motor vehicles and light trucks to use a dual service braking system, which provides back-up protection in the event of a brake fluid leak from one half of the system. Loss of brake fluid is the most common failure of service brakes, and contributes to many runaway accidents.

It should be noted that there are several manufacturers that supply mining motor vehicles (production, utility and personnel) with the dual service braking system.

Motor vehicles with a rated gross mass of 7,000 kg or more

Today, larger motor vehicles typically use hydraulically applied brakes involving a wet disc design. Some manufacturers incorporate brakes that can be either hydraulically applied or have a SA/HR system. Where SA/HR brakes are employed, they may serve the dual function of service and emergency brakes, provided all other requirements are satisfied. On some motor vehicles, the service brake function may also provide the same brake components used by the emergency / parking system but the systems are actuated by a different control system, which ensures compliance with the specific component in common requirements.

Motor vehicles having specialized brake systems

Some motor vehicles utilize other forms of braking systems. Service brake systems consisting of a closed loop pump and motor arrangement (hydrostatic drive) or an open loop pump, directional control valve, and motor arrangement (hydraulic drive). Either of these are used on motor vehicles of all sizes.

The requirements below for motor vehicles having specialized brake systems come from the recommendations of the best industry practice and are based on field experience and testing.

A hydrostatic drive is considered to be capable to perform as a service brake system providing that the following conditions are met:

• It cannot be disengaged from the remaining drive-train during travel unless emergency brakes apply automatically; and
• The system can be readily controlled to provide the required brake effect including back throttling (applying drive in the opposite direction) to compensate for inherent system bypass leakage; or
• It engages automatically to reduce the motor vehicle’s speed when the mechanical brake control is actuated on motor vehicles.

A hydraulic drive is considered capable to perform as a service brake system providing that all of the following conditions are met:

• It cannot be disengaged from the remaining drive-train during travel unless emergency brakes apply automatically;
• The directional control valve or additional control valves in the circuit are capable of blocking the flow of oil to and from the motor to provide the required brake effect; and
• The system can be readily controlled to provide the required brake effect including back throttling (applying drive in the opposite direction) to compensate for inherent system bypass leakage.

Note: A hydrostatic or hydraulic drive system which is used to propel a motor vehicle and meets the criteria set out above is considered capable of performing as a service brake system whether functioning alone or in combination with a mechanical brake.

Other brake systems may exist and should be addressed individually to determine if they meet all regulatory requirements.

This section describes terminologies that may not be defined in Regulation 854 but are commonly used in the mining industry and may be mentioned in the Regulation. The descriptions that follow are provided for the purpose of general reference.

Brake systems

A brake system generally refers to all of the components that combine together to stop and/or hold the motor vehicle. It consists of a control, means of brake actuation (i.e. pedal, cables, linkage, control valves, hoses, etc.), and the brake(s). The retarders, neutralizer and inching devices are not part of a brake system.

The CSA-M3450-03 and ISO 10265 standards referred to in subsections 119.1(2) and (3) require that a brake system must not contain a disconnect, such as a clutch or shiftable gearbox, which would allow the brake(s) to be disabled. A power source disconnect designed for starting vehicles in cold weather, which can also be used to disable a brake system, require the parking brake to be applied prior to disconnection. Every motor vehicle to which the standards referred to in subsections 119.1(2) and (3) apply must meet these requirements.

It is considered good practice that tow units be of suitable size, braking performance and stability to manage and safely stop a trailer without trailer axle brakes. The tow unit brake system must be tested to ensure its compliance with the requirements of the Regulation. The trailer and any payload on the trailer or tow vehicle are considered part of the tow vehicle’s gross tested vehicle weight for the purpose of subsection 119(7).

Retarders

Retarders generally refer to an energy-absorption component normally used to control the speed of the motor vehicle. As per section 119(3) of the Regulation, the effect of the retarder is not to be considered when determining brake performance system capacity.

Some motor vehicles may be equipped with additional controls that affect transmission operation, such as:

• Neutralizer devices that are not involved in the brake system but allow the transmission to be disengaged.
• Inching devices that neutralize a closed loop hydrostatic transmission control but leaves the transmission system engaged.

Common components

Common components generally refer to components that perform a function in two or more brake systems (refer to applicable CSA-M424.3-M90, CSA-M3450-03 or ISO 10265 standards).

Service brake system

A service brake system generally refers to a primary system used for stopping and holding the motor vehicle. Motor vehicles must meet the service brake performance requirements set out in section 119.1 of the Regulation.

Every motor vehicle to which the CSA-M3450-03 standard applies referenced in subsection 119.1(2) must meet the following requirements:

• If other systems are provided with power from the service brake system, any failure in these systems must be considered to be the same as a failure in the service brake system.
• Each wheel of at least one axle must have a service brake system of equal nominal capacity rating.
• Motor vehicles with semi-trailed units must have a service brake system that applies to at least one axle of the towing vehicle and one axle of the semi-trailed units.
• Note that semi-trailed units have one end of the trailer directly connected to and carried by the power unit, whereas a regular trailer is connected to the power unit via a tongue connected to a rear mounted hitch.
• Each motor vehicle must have a modulated service brake system. Vehicles not manned and operated under remote control may be accepted (where applicable) due to remote control system limitations or design. Modulated braking means the capability to continuously and progressively increase and decrease the braking force by operation of the brake control.

Secondary brake system

Secondary brake system refers to the “emergency brake system” defined in subsection 119(1) of Regulation 854.

Motor vehicles must meet the secondary brake system configuration and performance requirements of the applicable standard noted under section 119.1 of the Regulation.

Motor vehicles must meet the parking brake requirements under section 119.1 of the Regulation.

Parking brake systems should be capable of holding the machine in both the forward and reverse directions and with the load specified in the applicable standards CSA-M424.3-M90, CSA-M3450-03 or ISO 10265.

The CSA-M3450-03 and CSA-M424.3-M90 standards require that the parking brake system must not depend on an exhaustible energy source or additional operator input after the parking brake is applied.

The parking brake system may use common components of other brake systems provided the requirements of the applicable CSA-M424.3-M90, CSA-M3450-03 or ISO 10265 standards are met.

Warning device for stored energy sources (surface application)

Under section 119.2(3), if stored energy is used to apply the service brake system on surface vehicles, that system must be equipped with a warning device.

The device should readily attract the operator’s attention by providing a continuous visible and/or audible warning. Gauges indicating pressure or vacuum do not meet this requirement (refer to the applicable CSA-M424.3-M90 or CSA-M3450-03 standards).

For the purposes of brake systems, stored energy refers to hydraulic or pneumatically actuated systems that employ accumulators which store energy for application purposes. It does not refer to spring-applied systems.

The phrase "can be safely stopped", in subsection 119.2(3), means that the pressure used to actuate the brakes (stored energy) is still sufficient to generate adequate brake force to stop the vehicle within the stopping distance criteria as spelled out under the applicable CSA standard. Depending upon the configuration of the braking system the operator may or may not have time to react to degradation in the stored energy pressure level. For example a slow leak in an air-actuated system may take seconds or even minutes for the pressure to drop below critical pressure due to the large volumes involved vs. a hose leak in a hydraulic system that has much less volume and therefore pressure degrades much faster.

Automatic brake application (ABA)

A motor vehicle operating underground that has a hydraulic or pneumatic stored energy braking system must be equipped with a device that automatically applies the secondary braking system and stops the motor vehicle before the vehicle’s stored energy braking system, torque converter or transmission reaches the critical level of pressure as per subsections 119.2(1) and (4)(a) of the Regulation.

Warning device for ABA (underground application)

As per clause 119.2 (4) (b) of the Regulation, a motor vehicle equipped with ABA must be equipped with a device that warns the operator that the vehicle’s emergency brake system is about to be applied.

Although it is not required by the Regulation this device should activate at a setting 20% higher than the secondary brake activation pressure.

Brake latch reset

Subsection 119(9) requires that the emergency brake system be set up so that, whether the brake is applied automatically or manually, a deliberate act is required to release it.

More information

• Mining Safety
• Health and Safety Ontario
• Workplace Safety North
• Canadian Standards Association (CSA) standards referenced in in occupational health and safety legislation

Toll-free number

Call 1-877-202-0008 any time to report critical injuries, fatalities or work refusals. Call 8:30 a.m. to 5 p.m. Monday to Friday for general questions about workplace health and safety. Always call 911 in an emergency.

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