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GB/T 26777-2023 PDF in English


GB/T 26777-2023 (GB/T26777-2023, GBT 26777-2023, GBT26777-2023)
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GB/T 26777-2023: PDF in English (GBT 26777-2023)

GB/T 26777-2023
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 43.040.01
CCS T 70
Replacing GB/T 26777-2011
Trailer Landing Gears
ISSUED ON: NOVEMBER 27, 2023
IMPLEMENTED ON: JUNE 1, 2024
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 6
2 Normative References ... 6
3 Terms and Definitions ... 6
4 Types and Basic Parameters ... 7
5 Technical Requirements ... 8
6 Test Methods ... 12
7 Inspection Rules ... 21
8 Marks and Instruction Manual ... 22
Bibliography ... 24
Trailer Landing Gears
1 Scope
This document specifies the types and basic parameters, technical requirements, test methods,
inspection rules, marking and instruction manual of trailer landing gears.
This document is applicable to landing gears installed and used on freight trailers (except
center-axle vehicle transport trailers).
2 Normative References
The contents of the following documents constitute indispensable clauses of this document
through the normative references in the text. In terms of references with a specified date, only
versions with a specified date are applicable to this document. In terms of references without a
specified date, the latest version (including all the modifications) is applicable to this document.
GB/T 3766 Hydraulic Fluid Power - General Rules and Safety Requirements for Systems and
Their Components
JB/T 5000.3 Heavy Mechanical General Technique - Part 3: And Standards Welding
QC/T 484-1999 Automobile Paint Coating
3 Terms and Definitions
The following terms and definitions are applicable to this document.
3.1 trailer landing gears
A device installed on a trailer to support the trailer and maintain it stable when the towing
vehicle is detached from the trailer.
NOTE: it generally includes landing legs, handles, connecting rods, fixed frames and diagonal
braces, etc.
3.2 landing leg
An assembly of load-bearing components of the landing gears.
NOTE: it is generally divided into left landing leg and right landing leg, and mainly includes outer
leg, inner leg, base, driving mechanism and transmission mechanism, etc.
3.3 lifting load
speed gear transmission.
5.1.3 The landing gears shall have self-locking properties. In the propped up (working) state,
the outer legs shall not fall; in the vertically suspended (non-working) state, the inner legs shall
not fall by themselves.
5.1.4 The inner legs of the landing gears shall have limit marks and limit devices to prevent the
inner legs from falling off if the specified stroke is exceeded.
5.1.5 The landing gears shall have sealing protection properties to prevent the entry of
impurities that may weaken the functions or mechanical efficiency.
5.1.6 When the landing gears are working, they shall be able to flexibly rise and fall without
any obstruction.
5.1.7 The welds of the landing gears shall be uniform and straight, without defects, such as:
cracks, slag inclusions, pores, undercuts, spatters and missing welds, etc., and comply with the
requirements of JB/T 5000.3.
5.1.8 The rated operating voltage of electromechanical and electrohydraulic landing gears shall
be DC 12 V or 24 V.
5.1.9 The manual hydraulic and electrohydraulic landing gears shall be equipped with a
hydraulic fail-safe device to prevent the trailer from tipping due to hydraulic system faults.
5.1.10 For the landing gears equipped with a hydraulic system, the hydraulic system shall
comply with the stipulations of GB/T 3766, and shall satisfy the following requirements:
a) Under the specified conditions of use, the seals of all pipelines, components,
detachable joints and movable connections are properly sealed, without any leakage;
b) When withstanding 1.25 times the rated working pressure, the components are not
damaged or deformed, and the sealing performance complies with the stipulations of
a);
c) The burst pressure of hoses and hose joints is not lower than 4 times the rated working
pressure of the system.
5.2 Requirements for Interchangeability and Main Parameters
5.2.1 The adjustable stroke and main technical parameters of the landing gears shall comply
with the relevant stipulations of Table 1.
L2---the distance from the center of the transmission connecting rod to the uppermost end surface of the
landing leg;
L3---the distance from the first mounting hole to the top plate;
n  57---n is the number of hole spacing of mounting holes in the same row; 57 is the hole spacing;
H---the closing height of the landing gears;
S---the stroke of the landing gears.
Figure 3 -- Interchangeable Dimensions of Landing Gears
5.3 Performance Requirements
5.3.1 The landing gears shall be tested for lifting capacity in accordance with the stipulations
of 6.2. The lifting load and corresponding torque shall comply with the stipulations of Table 1.
5.3.2 The manual mechanical type and electromechanical type of landing gears shall be tested
for lifting stroke in accordance with the stipulations of 6.3. The lifting stroke of the power input
spindle for one rotation shall not be less than 0.6 mm.
5.3.3 After the landing gears are subject to the load-bearing capacity test in accordance with the
stipulations of 6.4, there shall be no structural damage and abnormal wear, etc. (except for
wearing parts), and they shall still be able to normally operate. The hydraulic system of the
hydraulic type landing gears shall not leak, and the sinkage shall not be greater than 5 mm.
5.3.4 After the landing gears are subject to the longitudinal and transverse strength test in
accordance with the stipulations of 6.5, they shall be able to normally expand and retract under
the no-load condition. During expansion and retraction, the torque required by the mechanical
landing gears shall be less than 67 N  m, and the hydraulic system of the hydraulic type landing
gears shall not leak.
5.3.5 After the landing gears are subject to the vertical strength test in accordance with the
stipulations of 6.6, they shall be able to normally expand and retract under the no-load condition.
During expansion and retraction, the torque required by the mechanical landing gears shall be
less than 67 N  m, and the hydraulic system of the hydraulic type landing gears shall not leak.
5.3.6 After the landing gears are subject to the no-load operation test in accordance with the
stipulations of 6.7, there shall be no structural damage and abnormal wear, etc., and they shall
still be able to normally operate.
5.3.7 After the landing gears are subject to the reliability test in accordance with the stipulations
of 6.8, there shall be no structural damage and abnormal wear, etc., and they shall still be able
to normally operate.
5.3.8 After the landing gears are subject to the stability test in accordance with the stipulations
of 6.9, there shall be no structural damage, permanent deformation and abnormal wear, etc.,
and they shall still be able to normally operate.
5.3.9 After the landing gears used for multimodal trailers are subject to 1,000 times of dynamic
load-bearing test in accordance with the stipulations of 6.10, there shall be no structural damage,
permanent deformation and abnormal wear, etc., and they shall still be able to normally operate.
5.3.10 After the landing gears used for multimodal trailers are subject to the impact test in
accordance with the stipulations of 6.11, there shall be no structural damage and abnormal wear,
etc., and they shall still be able to normally operate.
6 Test Methods
6.1 Test Requirements
The installation of auxiliary connectors and landing gears used for the tests shall comply with
the manufacturer’s design requirements. During the tests, necessary maintenance can be
performed in accordance with the manufacturer’s regulations.
6.2 Lifting Capacity Test
6.2.1 In accordance with the method recommended by the manufacturer, vertically install the
landing gears on a special-purpose testing machine, fix and tightly lock it.
6.2.2 Operate the landing gears to extend the inner leg by 370 mm (if the stroke is less than 395
mm, extend the maximum stroke, and then, retract by 25 mm), along the F1 direction shown in
Figure 4, load it to the lifting load.
6.2.3 Use the low-speed gear to operate the mechanical type of landing gears, so that the inner
leg extends by 25 mm at a constant speed. Measure and record the torque for no less than 10
times and calculate the average value.
6.2.4 Operate the hydraulic type of landing gears, so that the inner leg extends by 25 mm at a
constant speed. Measure and record the hydraulic system pressure for no less than 10 times,
and the average value shall not be greater than the specified rated working pressure.
......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.