GB/T 27697-2024Hydraulic bottle jacks (English PDF)

1 Scope

This document specifies the types, the basic parameters and the technical requirements of hydraulic bottle jacks of rated capacity not greater than 500 t, describes the corresponding test methods and specifies the inspection rules and the marking, packaging, transport and storage.

This document applies to hydraulic bottle jacks used in the motor vehicle, machinery, shipbuilding, building and metallurgical industries and similar sectors.

3 Terms and definitions

3.1 hydraulic bottle jack: a light and small lifting appliance of vertical construction which uses hydraulic oil as the working medium and a ram or hydraulic cylinder as the rigid lifting member, and which raises a load through its bearing surface within its stroke.

3.2 rated capacity, Gn: the maximum load a hydraulic bottle jack is permitted to raise through its whole stroke under normal working conditions.

3.3 lowest height, H: the vertical distance from the bearing surface to the bottom supporting surface when the piston rod and the adjusting screw of the jack are fully retracted.

3.4 lifting height, H1: the vertical distance through which the bearing surface of the jack rises from the lowest height position to the position of reliable stop.

3.5 adjusting height, H2: the vertical distance through which the adjusting screw of the jack rises from the fully retracted state to the position of reliable stop.

3.6 load limiting device: the safety device that prevents overload in the hydraulic system of the jack. Note: it is usually a relief valve.

3.7 press down force for piston rod: the force applied to the bearing surface of the jack, with the return valve fully open, which makes the piston rod descend.

3.8 duty: the statement of the series of load conditions to which the motor is subjected, including starting, electrical braking, no-load running, stopping and de-energizing, together with their duration and their sequence.

4 Types and basic parameters

By constructional type, hydraulic bottle jacks are divided into single-stage piston rod jacks and multi-stage piston rod jacks. By method of operation they are divided into manual hydraulic bottle jacks and hydraulic bottle jacks with another power source, whether pneumatic, electric or otherwise. Typical examples are shown in Figure 1, whose reference numbers denote the adjusting screw, the piston rod, the matching handle, the pawl lever, the pump plunger, the base, the return valve, the tension spring, the air hose, the control switch, the air pump, the power plug and the electric motor, and whose symbols denote the lowest height H, the lifting height H1 and the adjusting height H2.

The basic parameters of the jack are the rated capacity Gn, the lowest height H, the lifting height H1 and the adjusting height H2. The rated capacities recommended for preferential use are 2, 3, 5, 8, 10, 12, 16, 20, 32, 50, 70, 100, 200, 320 and 500 tonnes.

5 Technical requirements

The surface coating of the jack shall adhere firmly and be even and uniform in colour, without evident spots, wrinkled skin, blisters or sagging; bare machined surfaces shall be given rust protection; the bearing surface of the jack shall have a non-slip form; and the hydraulic system shall be well sealed, without seepage at the fixed seals, a film of oil being allowed at the moving seals.

On a jack fitted with an adjusting screw, the screw shall turn freely and shall be prevented from coming out of the piston rod.

A jack with another power source shall be operated by a control switch; the switch shall be marked with the direction of movement, the marking being firm, clear and easy to read, and the jack shall stop moving at once as soon as the operator releases the switch.

The lowest height of the jack shall not be greater than the value declared for the product, and the lifting height and the adjusting height shall not be less than the values declared.

The jack shall have a relief valve to prevent overload, whose opening load shall lie between the rated capacity and 1.15 times the rated capacity. The jack shall have a reliable stop device, which shall prevent the piston rod from coming out of the assembly.

When the press down force given in Table 1 is applied, the piston rod shall be able to descend to its lowest position; a jack fitted with an automatic return device shall return automatically. In Table 1 the force is not more than 220 N for a single-stage piston rod and not more than 350 N for a multi-stage piston rod where the rated capacity is not more than 16 t; not more than 445 N and not more than 700 N respectively where the rated capacity is above 16 t and below 100 t; and not more than 785 N and not more than 1 000 N respectively where the rated capacity is 100 t or more.

Under a test load equal to the rated capacity, the mean speed at which the piston rod descends once the return valve has been opened shall be controllable within 0.15 m/s. Under a test load of 1.25 times the rated capacity, the vertical descent of the piston rod shall be not more than 0.7 mm in the first minute and not more than 1 mm in 10 min.

When the jack raises the rated capacity with the handle supplied, the handle operating force shall be not more than 400 N; on a jack that works with more than one pump, the handle operating force with each pump working separately shall likewise be not more than 400 N.

The jack shall withstand a rated load test at the rated capacity. After the test, the visible sealing surfaces of the piston rod and of the pump plunger shall show no scoring that affects performance, the fixed seals shall not leak oil, a film of oil only being allowed at the moving seals, the adjusting screw shall still turn freely, the stop shall remain reliable and the performance of the machine shall not have failed.

The jack shall withstand a static load test at 1.5 times the rated capacity. After the test there shall be no permanent deformation, oil leakage or other abnormality that affects the performance of the machine in use, and the adjusting screw shall still turn freely. The jack shall withstand a dynamic load test at 1.25 times the rated capacity, and on an inclined surface a dynamic load test at the rated capacity, with the same requirements after each test.

Under a test load equal to the rated capacity, the number of continuous full-stroke operating cycles shall be not less than the number given in Table 2, and after the test the performance of the machine shall not have failed and it shall still work normally. Table 2 requires 100 cycles for a single-stage and 70 for a multi-stage piston rod where the rated capacity is not more than 20 t; 30 and 22 respectively where the rated capacity is above 20 t and below 100 t; and 15 and 10 respectively where the rated capacity is 100 t or more.

The jack shall work normally in an ambient temperature from minus 20 degrees Celsius to 50 degrees Celsius, the hydraulic system remaining well sealed, without seepage at the fixed seals and with a film of oil allowed at the moving seals.

Where the jack weighs more than 10 kg, not counting the handle, it shall be fitted with a carrying handle or a moving device. A single carrying handle shall withstand twice the weight of the jack without visible permanent deformation.

The electrical system of an electric jack shall conform to GB/T 5226.32. For an electric jack powered from a vehicle cigarette lighter socket, the maximum input power shall not exceed 120 W.

6 Test methods

Visual inspection covers the appearance quality of the jack, the effectiveness of the sealing and the non-slip form of the bearing surface. The adjustment check is made with the jack unloaded, the adjusting screw being turned by hand to check its rotation and its stop. The control switch check consists of inspecting the firmness of the marking, which shall not lift or peel off, and of connecting the jack with another power source to that source and operating and releasing the control switch at least three times with the jack unloaded, to check how the jack runs and whether the direction shown by the marking matches the direction of movement.

Dimensional check. The jack is placed on a flat plate with the piston rod and the adjusting screw fully retracted and the vertical distance from the bearing surface to the bottom supporting surface, that is the lowest height H, is measured; the jack is then operated to raise the piston rod to the position of reliable stop and the lifting height H1 is measured; on a jack with an adjusting screw the screw is raised to the stop position and the adjusting height H2 is measured.

Relief valve test. The jack is placed beneath a force measuring device and operated until the bearing surface touches the device, then operated further until the relief valve opens; the steady load shown by the device at that moment is the opening load of the relief valve. A multi-stage jack is tested with the last stage extended, although for the piece-by-piece inspection the first stage extended is allowed.

Stop check. With the jack secured against overturning, the jack is operated to raise the piston rod until the stop device acts, and the stop is checked. On a jack where operating the handle at the stop position would open the relief valve, the handle shall be operated until the relief valve opens, in order to check that the stop device is reliable.

Press down force test and return valve test. With the piston rod at the lifting height position, the return valve is fully opened and the press down force of Table 1 is applied vertically to the bearing surface, the descent of the piston rod being observed; on a jack with an automatic return device the return of the rod is observed. For the return valve test, with the piston rod at the lifting height position, a test load equal to the rated capacity is applied to the bearing surface, the return valve is opened and its opening controlled, and the distance and time taken by the piston rod to descend from the start to one tenth of the lifting height are recorded, from which the mean descent speed is calculated.

Descent test. The piston rod is raised to half the lifting height, or, on a multi-stage jack, to half the stroke of the last stage; a test load is applied gradually to the bearing surface up to 1.25 times the rated capacity, timing begins when 1.25 times the rated capacity is reached, and the vertical descent of the piston rod at 1 min and at 10 min is measured.

Handle operating force test. Under a test load equal to the rated capacity the jack is raised and the maximum operating force is measured at a point 50 mm from the end of the handle supplied, within a range of 30 degrees from the horizontal, the force being applied perpendicular to the axis of the handle. A multi-stage jack is tested with the last stage extended. On a jack that works with more than one pump, a pump marked as suitable only for raising without load need not be tested for handle operating force.

Rated load test. A test load equal to the rated capacity is applied to the bearing surface and the jack is operated to raise the piston rod from its lowest position to the lifting height position, or, for a jack of more than 32 t, from the half-stroke position to the lifting height position, three raising and lowering cycles being carried out. A jack with more than one power source shall be tested with each power source separately, and a jack fitted with an adjusting screw shall have the screw raised to the stop position.

Static load test. The piston rod is raised to two thirds of the lifting height, or, on a multi-stage jack, to half the stroke of the last stage; on a jack with an adjusting screw the screw is raised to the stop position; a test load of 1.5 times the rated capacity is applied to the centre of the bearing surface and held for 15 min.

Dynamic load test and stability test. For the dynamic load test the relief valve is disabled, a test load of 1.25 times the rated capacity is applied to the bearing surface and the jack is operated to raise the piston rod from its lowest position to the lifting height position, one raising and lowering cycle being carried out. For the stability test the relief valve is disabled and the jack is placed on a hard supporting surface at 5 degrees to the horizontal, with no oil or other foreign matter between the two contact surfaces; a test load equal to the rated capacity is applied vertically at the centre of the bearing surface and the jack is operated through one raising and lowering cycle from the lowest position to the lifting height position. In both tests a jack fitted with an adjusting screw shall have the screw raised to the stop position, and a jack with more than one power source shall be tested with each source separately; for the dynamic load test another handle may be used.

Continuous operation test. A test load equal to the rated capacity is applied to the bearing surface, the adjusting screw of a jack so fitted is raised to the stop position, and the piston rod is worked to and fro from the lowest position to the lifting height position for the number of cycles given in Table 2. A jack with more than one power source shall be tested with each source separately, and different jacks may be used for the tests. A pause of 2 min is allowed after each cycle, and for an electric jack the pause may follow the duty. Where a handle is fitted, another handle may be used, and during the pause the moving joints of the transmission may be lubricated.

High and low temperature performance test. The return valve is opened so that the piston rod is at its lowest position and the jack is placed in turn in a high temperature environment of 50 degrees Celsius and a low temperature environment of minus 20 degrees Celsius. In the high temperature environment it is laid on each of its two sides for 2 h; then, at room temperature, a test load equal to the rated capacity is applied to the bearing surface and a manual jack is worked to and fro twelve times with the handle, or a jack with another power source is run continuously for 15 s, and the working of the jack is checked. It is then held in the low temperature environment for 4 h and the same room temperature test is repeated. The whole process from taking the jack out of the high or low temperature environment to the end of the test shall be completed within 1 min.

Carrying handle strength test. The jack is lifted clear of the ground by the carrying handle with a lifting attachment, and one jack of the same kind, or a weight equal to the weight of the jack, is hung on the body; it is left hanging for 3 min and the condition of the handle is checked. A jack with more than one carrying handle shall be tested on each handle separately.

Maximum input power test. At room temperature the electric jack is connected to a stable power supply whose output voltage matches the product marking, and is placed under a fixed device; the jack is operated so that the bearing surface rises into contact with the device and is then operated further until the relief valve opens. The peak values of voltage and current during the operation are measured and the maximum power is calculated from them. A multi-stage jack shall be tested with the last stage extended.

7 Inspection rules

Inspection of the jack is divided into factory inspection and type inspection. Factory inspection comprises piece-by-piece inspection and sampling inspection. Every jack shall undergo factory inspection by the manufacturer and may leave the works only with a certificate of conformity once it has passed. The inspection items are listed in Table 3, which pairs each item with the technical requirement and the test method that govern it and shows whether it belongs to the piece-by-piece inspection, to the sampling inspection or to the type inspection. Only the visual inspection and the relief valve test are carried out on every unit; the adjustment check, control switch check, dimensional check, stop check, press down force test, return valve test, descent test and rated load test are carried out on the sample; and the handle operating force test, static load test, dynamic load test, stability test, continuous operation test, high and low temperature performance test, carrying handle strength test and maximum input power test are carried out only in the type inspection.

The sample for the sampling inspection is drawn from products that have passed the piece-by-piece inspection, at 0.20 % of each batch of each size, and not fewer than 3 units. If one unit fails, the failed item shall be inspected on twice the number of units; if more than one unit fails at the first attempt, or if failures persist on the doubled inspection, the failed item shall be inspected on the whole batch.

Type inspection shall be carried out in any of the following cases: a) the trial and approval of a new product, or of an existing product whose manufacture is transferred to another works; b) after regular production has begun, where a considerable change in structure, material or process may affect the performance of the product; c) when production is resumed after being suspended for a year or more; d) when the result of the factory inspection differs considerably from that of the previous type inspection; e) when an interested party asks for a type inspection.

Type inspection covers the items of Table 3 one by one, on not fewer than 3 units each time, of which one unit undergoes only the continuous operation test and two units undergo all the items other than the continuous operation test. For a jack with several power sources, one further unit is added for each additional power source and undergoes only the continuous operation test. If one unit fails, the failed item shall be inspected on twice the number of units; if more than one unit fails at the first attempt, or if failures persist on the doubled inspection, the type inspection is not passed.

8 Marking, packaging, transport and storage

Every jack shall carry a nameplate in a conspicuous position giving at least the name of the manufacturer, the name and model of the product, and the basic parameters, which include the rated capacity, the lowest height and the lifting height, and where applicable the adjusting height, the rated air pressure, the rated voltage, the rated power and the duty.

Every jack and every instruction manual shall carry warning marks that prompt the operator to work safely. The warning marks shall state the following, or use wording or pictures of the same effect: read and understand the whole of the instruction manual before operating the device; never overload it; use it only on a level, hard supporting surface; use it for lifting only, never as a support; and be aware that the jack carries potential risks including the load dropping or overturning, so that no one may work under a load held up by the jack alone.

The marking on the packing case shall be neat and clear and shall give at least the model, name and quantity of the product, the number of the standard applied, the outline dimensions and the mass of the case, and the name and address of the manufacturer and the date of manufacture. The jack shall be secured firmly inside the case, the case shall be sturdy and shall keep out damp effectively.

Every jack shall be accompanied by at least a packing list, an instruction manual and a certificate of conformity. The instruction manual shall be clear and easy to understand and shall cover, besides the requirements of 8.1, the correct method of operation, the precautions and the type of hydraulic oil; the instruction manual of an electric jack shall include the electrical schematic diagram.

During transport the jack shall be handled gently to avoid damage and knocks, and it shall be stored in a warehouse that is well ventilated and protected against damp, sunlight and corrosion.