GB/T 18849-2023 Powered industrial trucks - Brake performance and component strength
1 Scope
This document specifies performance, test methods, controls, control forces and component strength for brake systems fitted to the following, as defined in ISO 5053-1:
——powered industrial trucks of all capacities;
——towing and pushing tractors up to and including 66750 N drawbar pull (hereafter referred to as industrial tractors);
——burden carriers; and
——industrial trucks handling freight containers.
Loss of electrical power and loss of any other form of power assistance is not covered by this document. Braking systems used in emergency situations (e.g. activating the emergency switch or control system shut down) are not covered in this document.
This document only includes requirements for newly manufactured trucks.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
braking force
force at the contact surface between a wheel and the ground, produced by the effect of a braking system (3.3), which opposes the speed or the tendency to movement of the truck
[SOURCE: GB/T 5620:2020, 9.11.3]
3.2
braking performance
performance of a braking system (3.3) as measured by the braking distance in relation to the initial speed of the truck and/or by braking force (3.1) and the capability to hold the truck at a standstill on a gradient
3.3
braking system
combination of parts which fulfil one or more of the following functions:
——control (usually to reduce) a truck’s speed;
——bring the truck to a halt or hold it stationary
[SOURCE: GB/T 5620-2020, 3.2]
3.4
cold brake
brake that meets one of the following conditions:
a) the temperature measured at the periphery of the disc or on the outside of the drum is below 100 °C;
b) in the case of totally enclosed brakes including oil-immersed brakes, the temperature on the outside of the housing is below 50 °C or within the manufacturer's specification;
c) the brake has not been operated in the previous 1 h
3.5
fade test
test procedure consisting of one or more brake applications or the continuous dragging of the brake to generate heat with the effect that differences in braking performance (3.2), if any, can be observed
[SOURCE: GB/T 5620-2020, 8.4, modified]
3.6
lining burnishing
pre-test conditioning procedure for obtaining a specified degree of geometric, physical and chemical adaptation between the brake lining surface and the drum or disc
3.7
laden mass
foreseen maximum laden truck mass likely to occur in the intended use of the truck, taking into account various combinations of optional equipment and the actual capacity applicable at the lift height specified for the tests (where relevant)
3.8
parking braking system
braking system (3.3) allowing a truck to be held stationary mechanically, even on an inclined surface, particularly in the absence of the operator
3.9
service braking system
braking system (3.3) allowing the operator to control, directly or indirectly, the speed of the truck or to bring the truck to a halt
3.10
stopping distance
s0
distance travelled by the truck during the total braking time, i.e. distance travelled by the truck from the instant when the driver begins to actuate the control device until the instant when the truck stops
Note: Control device is part of the braking system (3.3) which initiates its operation. Control devices of industrial trucks are defined in GB/T 10827.1-2014, 4.4.2.2, 4.4.2.3 and 4.4.2.4.
3.11
test speed
speed greater than 90 % of the maximum designed truck speed
Note: If the truck speed is automatically reduced in certain load conditions or load positions (i.e. lift height dependent), this reduced speed is the maximum travel speed for that load condition/position.
3.12
unladen mass
foreseen minimum unladen truck mass likely to occur in the intended use of the truck, taking into account various combinations of optional equipment
3.13
drawbar drag
steady state braking force (3.1) that can be applied to the ground by a mechanical braking system (3.3) at a given speed
4 Requirements
4.1 Required brake systems
The truck shall have the following brake systems:
——a service brake system;
——a parking brake system.
4.2 Operating means
The service and parking brakes shall be operated by means of independent systems. Both braking systems may utilize the same brakes; i.e. brake shoes, brake drums and related actuating items. Independent brake systems are not required to be fitted to stand-on and pedestrian controlled trucks as defined in ISO 3691-1.
4.3 Service braking system
All trucks shall meet the service brake requirements for:
- stopping distance (6.3.1) and heat fade test (6.5.2);
- drawbar drag test (6.3.2) and heat fade test (6.5.3); or
- alternative test procedure (6.3.3), e.g. calculation, and heat fade test simulation (6.5).
4.4 Parking braking system
The parking braking system shall meet the requirements of 6.2.
4.5 Brake control forces
4.5.1 The control forces to meet the required brake performances for the systems, as specified in 6.2 and either 6.3.1 or 6.3.2, shall not exceed the values given in 4.5.2 to 4.5.6 and summarized in Table 1.
Note: Other types of brake actuations are possible.
4.5.2 For brakes applied by depressing a pedal, the required service brake performance and parking brake performance shall be attained with a pedal force not greater than 450 N.
4.5.3 For brakes applied by an upward movement of a brake pedal (releasing the brake pedal), the required service brake performance and parking brake performance specified shall be attained with the pedal fully released. The force required to release the brakes and to hold the pedal fully depressed while travelling shall not be greater than 200 N.
4.5.4 For parking brakes applied by means of a hand lever, the required brake performance shall be attained when a force not greater than 300 N is applied to the hand lever at the gripping point.
4.5.5 For service brakes applied by squeezing a handgrip, the required brake performance shall be attained when a force not greater than 150 N is applied to the handgrip at the gripping point.
4.5.6 For brakes applied by means of a tiller which is biased, e.g. spring loaded, to the upright position (as on pedestrian controlled trucks), the required service brake performance shall be attained at the maximum depressed stroke position of the tiller when a force not greater than 150 N is applied at the mid-point of the handgrip.
4.6 Brake component strength
4.6.1 The strength of brake components shall not be lower than the values given in 4.6.2 to 4.6.6 and summarized in Table 1.
4.6.2 For trucks having a downward movement of a brake pedal (depressing the brake pedal) to apply the service or parking brake(s), the system shall be capable of withstanding a brake pedal force of at least 1200 N without any failure, cracking or deformation which affects the brake performance or function.
4.6.3 For trucks having an upward movement of a brake pedal (releasing the brake pedal) to apply the service or parking brake(s), the system shall be capable of withstanding a force of 200 % of the maximum possible setting of the spring which applies the brake(s), without any failure or cracking or any deformation which affects the brake performance or function.
The pedal when fully depressed, and its associated mechanical stop shall be capable of withstanding a force of 1800 N applied at the centre of the brake pedal actuating surface without any failure, cracking or deformation which affects the brake performance or function.
