CN218971557U

CN218971557U - Manual tray cylinder and tray truck using same

Info

Publication number: CN218971557U
Application number: CN202320060347.XU
Authority: CN
Inventors: 葛国安; 陈景璐
Original assignee: Ninghai Baicheng Machinery Co ltd
Current assignee: Ninghai Baicheng Machinery Co ltd
Priority date: 2023-01-06
Filing date: 2023-01-06
Publication date: 2023-05-05
Anticipated expiration: 2033-01-06

Abstract

The utility model discloses a manual tray cylinder and a tray truck applied by the same, wherein the manual tray cylinder comprises: the oil pump body is provided with a small oil cylinder part, and a first step is arranged in the small oil cylinder part; the small guide sleeve is arranged on the small oil cylinder part, and the bottom end of the small guide sleeve is combined with the first step to form a first closed-loop groove; a first oil seal mounted in the first closed-loop groove; a small piston rod reciprocally movable along an inner wall of the small guide sleeve between an extended position and a compressed position. The utility model provides a manual tray oil cylinder, which replaces a closed-loop groove structure in the prior art by a first closed-loop groove formed by combining the bottom end of a small guide sleeve and a first step, and can complete the assembly of a first oil seal by only unscrewing the small guide sleeve, so that the assembly difficulty is reduced, and the maintenance quality of the tray oil cylinder is improved.

Description

Manual tray cylinder and tray truck using same

Technical Field

The utility model relates to the technical field of tray cylinders, in particular to a manual tray cylinder and a tray truck using the same.

Background

The main structure of the manual hydraulic carrier is divided into: the device comprises a handle, an oil cylinder and a vehicle body. The manual hydraulic carrier handle plays a role of manually pressing, the handle is repeatedly rocked to press the small piston rod 3 'to control the lifting of the large piston rod 6' in the oil cylinder, the length of the handle is about 1 meter generally, and the labor is greatly reduced by utilizing the principle of a long handle.

Referring to fig. 1, the conventional oil seals 3 ', 4' are relatively inconvenient to assemble. For example, a closed-loop groove is processed on the inner wall of the small guide sleeve 1 ', an oil seal 3' is embedded and installed in the closed-loop groove, and the inner ring of the oil seal 3 'is sleeved on the periphery of the small piston rod 2' to form a seal. The oil seal 3' is difficult to install and detach in the closed-loop groove, and is difficult for non-professional staff to complete the work. Or, for example, the oil seal 4' is tightly attached in a closed-loop groove in the deep cavity, and the removal or the installation of the oil seal is very inconvenient.

Disclosure of Invention

The present utility model aims to solve at least one of the technical problems in the related art to some extent. Therefore, the utility model provides the manual tray oil cylinder, which replaces a closed-loop groove structure in the prior art by a first closed-loop groove formed by combining the bottom end of the small guide sleeve and the first step, and can complete the assembly of the first oil seal by unscrewing the small guide sleeve, so that the assembly difficulty is reduced, and the maintenance quality of the tray oil cylinder is improved.

The utility model also provides a manual tray oil cylinder, which replaces a closed-loop groove structure in the prior art by a second closed-loop groove formed by combining the bottom end of the large guide sleeve and the second step, and can complete the assembly of the second oil seal by only unscrewing the large guide sleeve, so that the assembly difficulty is reduced, and the maintenance quality of the tray oil cylinder is improved.

The utility model further provides a pallet truck comprising the manual pallet cylinder.

The technical scheme adopted by the utility model is as follows: provided is a manual tray cylinder including:

the oil pump body is provided with a small oil cylinder part, and a first step is arranged in the small oil cylinder part;

the small guide sleeve is arranged on the small oil cylinder part, and the bottom end of the small guide sleeve is combined with the first step to form a first closed-loop groove;

a first oil seal mounted in the first closed-loop groove;

a small piston rod reciprocally movable along an inner wall of the small guide sleeve between an extended position and a compressed position.

The beneficial effects of the structure are as follows: compared with the prior art, the closed-loop groove is machined on the inner wall of the oil cylinder, and the machining of the first step in the structure is simple and convenient, and has low requirements on a machined cutter. When the first oil seal is assembled or maintained, the small guide sleeve is more convenient to replace and only needs to be unscrewed, so that the requirement on the proficiency of maintenance workers is reduced, non-professional staff can also complete the work, and the success rate of maintaining the first oil seal is improved.

Specifically, a spring cover is arranged on the small piston rod, a spiral spring is sleeved on the periphery of the small oil cylinder part, and the upper end of the spiral spring is abutted against the spring cover; the spiral spring is arranged to provide power for the lifting handle, so that the labor-saving effect is achieved.

Specifically, the oil pump body is provided with two cylinder ears which are arranged at intervals, the cylinder ears are provided with limiting parts for clamping limiting rods, and the rod bodies of the limiting rods are propped against the upper ends of the spring covers, so that the small piston rods are kept at compression positions; before the product leaves the factory, the manufacturer of the manual tray cylinder needs to debug the small piston rod and repeatedly presses the small piston rod to detect whether an oil way is normal or not. In the downstream assembly link, when the forklift handle is assembled, the small piston rod is prevented from interfering with the forklift handle. The small piston rod is kept at a compression position by matching with a related fixture, and can be released after the forklift handle is assembled; through installing the gag lever post on the cylinder body ear for the extension of restriction little piston rod makes it keep in the compressed position, and the low reaches producer can accomplish the installation when assembling fork truck handle, need not to press the little piston rod twice, has reduced the assembly degree of difficulty of manual tray hydro-cylinder structure.

Specifically, at least one cylinder body lug is provided with a crescent moon piece, and the crescent moon piece is formed by outwards protruding side surfaces of the cylinder body lug.

Specifically, the cylinder body lug is provided with a shaft hole for installing a connecting shaft, the connecting shaft is provided with at least one elastic pin, and two ends of the elastic pin are arranged along the radial direction of the connecting shaft and are propped against the crescent moon piece; the manual tray hydro-cylinder is when dispatching from the factory attached the connecting axle on the cylinder body ear generally, and the setting of elastic pin avoids the connecting axle to drop at the in-process of transportation to the elastic pin offsets with the crescent moon piece, can restrict the connecting axle rotatory for the shaft hole.

A manual tray cylinder comprising:

the oil pump body is provided with a large oil cylinder part and a lifting cylinder, the upper end of the lifting cylinder extends to the inside of the large oil cylinder part, and a second step is arranged in the lifting cylinder;

the bottom end of the large guide sleeve is combined with the second step to form a second closed-loop groove;

a second oil seal mounted in the second closed-loop groove;

and the large piston rod reciprocates along the inner wall of the large guide sleeve.

The beneficial effects of the structure are as follows: compared with the prior art that a closed-loop groove is machined on the inner wall of the oil cylinder, the machining of the second step in the structure is simple and convenient, and the requirement on a machined cutter is low. When the second oil seal is assembled or maintained, the second oil seal is more convenient to replace, only the large guide sleeve is needed to be unscrewed, the requirement on the proficiency of maintenance workers is reduced, non-professional staff can also complete the work, and the success rate of maintaining the second oil seal is improved.

Specifically, the oil pump body has two cylinder body ears that the interval set up, have the spacing portion that is used for the joint gag lever post on the cylinder body ear, the shaft of gag lever post offsets with the upper end of spring cap, makes little piston rod keep in compression position.

Specifically, the oil pump body has two cylinder body ears that the interval set up, at least one the cylinder body is equipped with the crescent moon piece on the ear, the crescent moon piece by the outside protruding formation of cylinder body ear side.

Specifically, be equipped with the shaft hole that is used for installing the connecting axle on the cylinder body ear, be equipped with at least one elastic pin on the connecting axle, the both ends of elastic pin are followed the radial setting of connecting axle, and with the crescent moon piece offsets.

Specifically, the small guide sleeve is in threaded connection with the small oil cylinder part.

The pallet truck comprises any one of the manual pallet cylinders.

Drawings

In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the utility model, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a perspective view of a prior art manual tray cylinder;

FIG. 2 is a partial cross-sectional view of a manual tray cylinder in an embodiment of the utility model;

FIG. 3 is an enlarged view of a portion of FIG. 2 at A;

FIG. 4 is a partial enlarged view at B in FIG. 2;

FIG. 5 is a perspective view of a manual tray cylinder in an embodiment of the present utility model;

FIG. 6 is a schematic diagram of a manual tray cylinder according to an embodiment of the present utility model;

FIG. 7 is a partial perspective view of a manual tray cylinder in accordance with an embodiment of the present utility model;

FIG. 8 is a perspective view of an oil pump body according to an embodiment of the present utility model;

FIG. 9 is a cross-sectional view of an oil pump body in an embodiment of the present utility model;

FIG. 10 is a block diagram of a manual tray cylinder in an embodiment of the present utility model;

FIG. 11 is an enlarged view of a portion of FIG. 10 at C;

FIG. 12 is a schematic diagram of the overall structure of a manual tray cylinder in an embodiment of the present utility model;

FIG. 13 is a cross-sectional view of an oil pump body in an embodiment of the present utility model;

fig. 14 is a perspective view of a pallet truck according to an embodiment of the utility model.

The reference numerals in the figures illustrate:

1. an oil pump body; 2. a small piston rod; 3. a coil spring; 4. a small guide sleeve; 5. a large piston rod; 6. an oil drain valve; 7. a spring cover; 8. a large guide sleeve; 9. a first oil seal; 10. a first dust ring; 11. a second dust ring; 12. a second oil seal; 13. rod seal O-shaped ring; 14. a cylinder ear; 15. a limit rod; 16. a connecting shaft; 17. an elastic pin;

1a, a connecting part; 1b, a small oil cylinder part; 1c, lifting cylinders; 1d, a large oil cylinder part; 1e, a first step; 1f, a second step;

14a, a shaft hole; 14b, a crescent moon piece; 14c, a limiting part.

Detailed Description

Embodiments of the present utility model are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the utility model.

Examples

As shown in fig. 2 to 13, in the present embodiment, a manual tray cylinder is disclosed, including:

an oil pump body 1 having a small oil cylinder portion 1b, the small oil cylinder portion 1b having a first step 1e provided therein;

a small guide sleeve 4 mounted on the small oil cylinder part 1b, wherein the bottom end of the small guide sleeve 4 is combined with the first step 1e to form a first closed-loop groove;

a first oil seal 9 installed in the first closed-loop groove;

a small piston rod 2 reciprocally movable along the inner wall of said small guide sleeve 4 between an extended position and a compressed position.

Further, as shown in fig. 9 and 10, in the present embodiment, the oil pump body 1 has a flat plate-like connection portion 1a, a small oil cylinder portion 1b and a large oil cylinder portion 1d vertically provided on the connection portion 1a, wherein a pipe is provided inside the connection portion 1a to communicate the small oil cylinder portion 1b with the large oil cylinder portion 1 d. The connecting portion 1a is vertically provided with a lifting cylinder 1c, the lifting cylinder 1c and the large oil cylinder portion 1d are coaxially arranged, the lower end of the lifting cylinder 1c extends downwards to the bottom of the connecting portion 1a, and the upper end of the lifting cylinder 1c penetrates through the connecting portion 1a and extends into the large oil cylinder portion 1 d.

Further, as shown in fig. 10, the small cylinder portion 1b is formed to protrude from the upper surface of the connecting portion 1a and extend upward. The upper end opening of the small cylinder portion 1b is provided with a first step 1e, and a portion of the first step 1e having a larger inner diameter is located at an upper portion of the portion having a smaller inner diameter such that the step surface of the first step 1e is provided face-up.

Further, the connection portion 1a is provided with a drain valve 6, and the drain valve 6 is used for controlling the opening and closing of the oil passage between the small cylinder portion 1b and the large cylinder portion 1 d.

Further, as shown in fig. 7 to 9, in the present embodiment, the inner diameter of the small guide sleeve 4 is adapted to the outer diameter of the small piston rod 2, the upper end of the small piston rod 2 is a free end, and the lower end passes through the inside of the small guide sleeve 4. The periphery of the lower part of the small guide sleeve 4 is matched with the part with larger inner diameter on the first step 1 e. The lower end of the first oil seal 9 abuts against the step surface of the first step 1e, the upper end abuts against the lower end of the small guide sleeve 4, the outer ring abuts against the inner wall of the larger inner diameter portion of the first step 1e, and the inner ring is slidably engaged with the small piston rod 2.

Specifically, as shown in fig. 3 and 4, the small piston rod 2 is provided with a spring cover 7, the outer periphery of the small cylinder portion 1b is sleeved with a coil spring 3, the upper end of the coil spring 3 abuts against the spring cover 7, and the lower end abuts against the connecting portion 1 a.

Further, the small piston rod 2 reciprocates between the extended position and the depressed position relative to the small cylinder portion 1b, and the arrangement of the coil spring 3 makes the small piston rod 2 have an elastic tendency to be held in the extended position, so as to provide assistance for lifting the handle, and achieve the effect of saving labor.

Further, a first dust ring 10 is embedded and installed on the inner wall of the small guide sleeve 4.

Specifically, as shown in fig. 10 and 11, the oil pump body 1 has two cylinder ears 14 disposed at intervals, the cylinder ears 14 have a limiting portion 14c for clamping a limiting rod 15, and the rod body of the limiting rod 15 abuts against the upper end of the spring cover 7, so that the small piston rod 2 is kept in a compressed position.

Further, in the present embodiment, two cylinder lugs 14 are welded to the outer surface of the oil pump body 1, and the two cylinder lugs 14 are disposed in parallel at a distance. The lower end of the forklift handle is positioned between the two cylinder lugs 14 and is hinged with the cylinder lugs 14 respectively. The forklift handle is provided with a roller, and the roller is propped against the upper end of the small piston rod 2. When the forklift handle is rotated to swing relative to the cylinder lug 14, the roller repeatedly presses the small piston rod 2, so that the small piston rod 2 moves between the extension position and the compression position to do work back and forth, hydraulic oil is pumped into an oil way, and the large piston rod 5 is jacked.

Further, in the present embodiment, the small piston rod 2 has one maximum compression position, and a plurality of compression positions different in position between the maximum compression position and the extension position. The rod body of the limit rod 15 abuts against the upper end of the small piston rod 2, so that the small piston rod 2 is kept at any one of a plurality of compression positions, or the small piston rod 2 is kept at the maximum compression position, and interference of the small piston rod 2 to the installation of a subsequent forklift handle is avoided.

Specifically, in this embodiment, the limiting portion 14c is a notch structure, and is formed by recessing an edge of the cylinder ear 14. The opening of the notch structure faces downwards, and the limiting rod 15 can be clamped into the notch structure from bottom to top under the action of the small piston rod 2.

Specifically, as shown in fig. 12 and 13, in this embodiment, at least one cylinder ear 14 is provided with a crescent 14b, the crescent 14b is a semi-annular structure formed by protruding outwards from the side surface of the cylinder ear 14, the cylinder ear 14 is provided with a shaft hole 14a for installing a connecting shaft 16, the connecting shaft 16 is provided with at least one elastic pin 17, and two ends of the elastic pin 17 are arranged along the radial direction of the connecting shaft 16 and are abutted against the crescent 14 b.

Further, in the present embodiment, the connecting shaft 16 is fixed to the cylinder lug 14 by the elastic pin 17, wherein the connecting shaft 16 is fixed to the cylinder lug 14, and the forklift handle can rotate with respect to the axis around the connecting shaft 16. The two cylinder lugs 14 are respectively provided with a shaft hole 14a, and the forklift handle is rotatably arranged on the oil pump body 1 through a connecting shaft 16 matched with the shaft holes 14 a.

Examples

As shown in fig. 2-13, in this embodiment, a manual tray cylinder is disclosed, comprising:

an oil pump body 1 having a large oil cylinder portion 1d and a lift cylinder 1c, the upper end of the lift cylinder 1c extending into the large oil cylinder portion 1d, and a second step 1f being provided in the lift cylinder 1 c;

the large guide sleeve 8 is arranged on the large oil cylinder part 1d, and the bottom end of the large guide sleeve 8 and the second step 1f are combined to form a second closed-loop groove;

a second oil seal 12 mounted in the second closed-loop groove;

a large piston rod 5 which reciprocates along the inner wall of the large guide sleeve 8.

Further, as shown in fig. 5 to 7, the oil pump body 1 has a large oil cylinder portion 1d, a lifting cylinder 1c and a connecting portion 1a for communicating the oil paths of the small oil cylinder portion 1b and the large oil cylinder portion 1d, the upper end of the lifting cylinder 1c extends into the large oil cylinder portion 1d, a second step 1f is provided in the lifting cylinder 1c, a large guide sleeve 8 is mounted on the large oil cylinder portion 1d, the bottom end of the large guide sleeve 8 and the second step 1f are combined to form a second closed-loop groove for mounting a second oil seal 12, and a large piston rod 5 is slidably matched with the large guide sleeve 8, the second oil seal 12 and the large oil cylinder portion 1 d.

Further, in the present embodiment, the upper end opening of the lift cylinder 1c is provided with the second step 1f, and the portion of the second step 1f having the larger inner diameter is located at the upper portion of the portion having the smaller inner diameter such that the step surface of the second step 1f is provided facing upward. The inner diameter of the large guide sleeve 8 is matched with the outer diameter of the large piston rod 5, the upper end of the large piston rod 5 is used for lifting the frame, and the lower end of the large piston rod passes through the large guide sleeve 8. The periphery of the lower part of the large guide sleeve 8 is matched with the part with larger inner diameter on the second step 1 f. The lower end of the second oil seal 12 abuts against the step surface of the second step 1f, the upper end abuts against the lower end of the large guide sleeve 8, the outer ring abuts against the inner wall of the larger inner diameter portion of the second step 1f, and the inner ring slidably cooperates with the large piston rod 5.

Further, the large guide sleeve 8 is in sealing connection with the lifting cylinder 1c, so that an annular oil storage cavity is formed in the large oil cylinder part 1d, and the oil storage cavity is formed by enclosing the inner wall of the large oil cylinder part 1d, the lower part of the large guide sleeve 8 and the upper part of the lifting cylinder 1 c.

Specifically, the oil pump body 1 has two cylinder lugs 14 that set up at intervals, the last spacing portion 14c that is used for joint gag lever post 15 that has of cylinder lug 14, the shaft of gag lever post 15 offsets with the upper end of spring cap 7, makes little piston rod 2 keep in the compression position.

Specifically, as shown in fig. 10 and 11, the limiting portion 14c has a notch structure in the present embodiment, and is formed by recessing the edge of the cylinder ear 14. The opening of the notch structure faces downwards, and the limiting rod 15 can be clamped into the notch structure from bottom to top under the action of the small piston rod 2.

Specifically, the oil pump body 1 is provided with two cylinder lugs 14 arranged at intervals, at least one cylinder lug 14 is provided with a crescent piece 14b, and the crescent piece 14b is formed by outwards protruding side surfaces of the cylinder lugs 14.

Specifically, as shown in fig. 12 and 13, the cylinder ear 14 is provided with a shaft hole 14a for mounting a connecting shaft 16, the connecting shaft 16 is provided with at least one elastic pin 17, and two ends of the elastic pin 17 are disposed along the radial direction of the connecting shaft 16 and are abutted against the crescent 14 b.

Specifically, the inner wall of the large guide sleeve 8 is provided with a second dust ring 11 in a jogged manner, the inner wall of the large guide sleeve 8 is provided with a rod sealing O-shaped ring 13 in a jogged manner, the large guide sleeve 8 is in threaded connection with the large oil cylinder part 1d, and the small guide sleeve 4 is in threaded connection with the small oil cylinder part 1 b.

Examples

Referring to fig. 14, a pallet truck is disclosed in this embodiment, which includes the manual pallet jack described in embodiment 1.

Examples

As shown in fig. 14, a pallet truck is disclosed in this embodiment, which includes the manual pallet cylinder described in embodiment 2.

In the description of the present utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present utility model and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present utility model.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present utility model, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.

In the present utility model, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present utility model, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature "above," "over" and "on" a second feature may be a first feature directly above or obliquely above the second feature, or simply indicate that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present utility model. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

While embodiments of the present utility model have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the utility model, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the utility model.

Claims

1. A manual tray cylinder, comprising:

an oil pump body (1) having a small oil cylinder portion (1 b), wherein a first step (1 e) is provided in the small oil cylinder portion (1 b);

a small guide sleeve (4) arranged on the small oil cylinder part (1 b), wherein the bottom end of the small guide sleeve (4) is combined with the first step (1 e) to form a first closed-loop groove;

a first oil seal (9) mounted in the first closed-loop groove;

a small piston rod (2) which reciprocates along the inner wall of the small guide sleeve (4) between an extended position and a compressed position.

2. The manual tray cylinder according to claim 1, wherein: the small piston rod (2) is provided with a spring cover (7), the periphery of the small oil cylinder part (1 b) is sleeved with a spiral spring (3), and the upper end of the spiral spring (3) is abutted to the spring cover (7).

3. A manual tray cylinder as claimed in claim 2, wherein: the oil pump body (1) is provided with two cylinder lugs (14) which are arranged at intervals, the cylinder lugs (14) are provided with limiting parts (14 c) used for being clamped with limiting rods (15), and the rod bodies of the limiting rods (15) are propped against the upper ends of the spring covers (7) so that the small piston rods (2) are kept at compression positions.

4. A manual tray cylinder as claimed in claim 3, wherein: at least one cylinder body lug (14) is provided with a crescent (14 b), and the crescent (14 b) is formed by outwards protruding side surfaces of the cylinder body lug (14).

5. The manual tray cylinder as claimed in claim 4, wherein: the cylinder body lug (14) is provided with a shaft hole (14 a) for installing a connecting shaft (16), the connecting shaft (16) is provided with at least one elastic pin (17), and two ends of the elastic pin (17) are arranged along the radial direction of the connecting shaft (16) and are propped against the crescent moon piece (14 b).

6. The utility model provides a manual tray hydro-cylinder which characterized in that: comprising the following steps:

an oil pump body (1) having a large oil cylinder portion (1 d) and a lifting cylinder (1 c), wherein the upper end of the lifting cylinder (1 c) extends into the large oil cylinder portion (1 d), and a second step (1 f) is provided in the lifting cylinder (1 c);

the large guide sleeve (8) is arranged on the large oil cylinder part (1 d), and the bottom end of the large guide sleeve (8) and the second step (1 f) are combined to form a second closed-loop groove;

a second oil seal (12) mounted in the second closed-loop groove;

and the large piston rod (5) reciprocates along the inner wall of the large guide sleeve (8).

7. The manual tray cylinder as claimed in claim 6, wherein: the oil pump body (1) is provided with two cylinder lugs (14) which are arranged at intervals, the cylinder lugs (14) are provided with limiting parts (14 c) used for being clamped with limiting rods (15), and the rod bodies of the limiting rods (15) are propped against the upper ends of the spring covers (7) to enable the small piston rods (2) to be kept at compression positions.

8. The manual tray cylinder as claimed in claim 6, wherein: the oil pump body (1) is provided with two cylinder ears (14) which are arranged at intervals, at least one cylinder ear (14) is provided with a crescent piece (14 b), and the crescent piece (14 b) is formed by outwards protruding the side face of the cylinder ear (14).

9. The manual tray cylinder according to claim 8, wherein: the cylinder body lug (14) is provided with a shaft hole (14 a) for installing a connecting shaft (16), the connecting shaft (16) is provided with at least one elastic pin (17), and two ends of the elastic pin (17) are arranged along the radial direction of the connecting shaft (16) and are propped against the crescent moon piece (14 b).

10. A pallet truck, characterized in that: a hand operated pallet jack comprising any one of claims 1-9.