Disc brake operating mechanism and coal mining machine braking device with wear detection function

Abstract

The utility model relates to a disc brake operating mechanism and a coal mining machine braking device with wear detection, the operating mechanism comprises a warning screw, a screw plug and a single-rod piston cylinder, the front cavity and the rear cavity of the piston cylinder are respectively a rodless cavity and a rod cavity, the screw plug is installed on the cylinder wall of the front side of a cylinder barrel, the rear thread part of the warning screw is fixed in a piston, and the rear thread part of the screw plug is fixed in the piston. The front polish rod part penetrates through the screw plug and is connected with the screw plug in a front-back sliding mode, and a warning mark arranged on the polish rod part is located in front of the cylinder barrel; the brake device comprises a shell, a rear cover, a spline housing, a brake assembly and the control mechanism, the cylinder barrel, the shell and the rear cover are sequentially arranged from front to back and coaxially and fixedly connected, a round groove is formed in the extending end of the piston rod, and the front portion and the rear portion of the spline housing are arranged in the round groove and a central through hole of the rear cover respectively. The brake assembly is arranged between the spline housing and the shell in the radial direction, and the piston rod and the rear cover axially limit the brake assembly from front to back. The appearance of the device can reflect the abrasion condition, and underground maintenance and use are facilitated.

Description

Technical Field

[0001] The utility model relates to a disc brake operating mechanism and a coal mining machine braking device applying the mechanism. As the operating mechanism is provided with a friction plate wear detection structure, the coal mining machine braking device has a wear detection function. Background Art

[0002] As a shearer's anti-skid device, the brake directly impacts coal mine safety. When the shearer is stopped, the brake is engaged, preventing it from sliding down at a certain angle. When the unit's start command is issued, the brake quickly releases, allowing the shearer to begin moving.

[0003] Existing shearer brakes typically use disc friction pads, which gradually wear and become thinner during use. When they become thin enough, they no longer reliably engage the brake and need to be replaced. However, existing shearer brakes lack a convenient way to detect the extent of friction pad wear, making them inconvenient for underground maintenance. Utility Model Content

[0004] The utility model provides a disc brake operating mechanism and a coal mining machine braking device with wear detection function, which can conveniently grasp the wear degree of the disc brake friction plate.

[0005] The main technical solutions of this utility model are:

[0006] A disc brake operating mechanism includes a warning screw, a screw plug and a single-rod piston cylinder, the front and rear chambers of the single-rod piston cylinder are respectively a rodless chamber and a rod chamber, a spring is provided in the rodless chamber, the spring is kept in a compressed state, the rod chamber is connected to the hydraulic control circuit, the middle part of the piston of the piston cylinder is provided with a central threaded hole that passes through the front and back, a screw plug mounting through hole is provided on the front side wall of the cylinder barrel of the piston cylinder, the screw plug is installed in the screw plug mounting through hole, the rear end portion of the warning screw is a threaded portion, and the front is a smooth rod portion, and a radially outward protruding flange is between the threaded portion and the smooth rod portion, the threaded portion of the warning screw is threadedly connected to the central threaded hole, and the flange is used for axial positioning of the warning screw relative to the piston, the smooth rod portion of the warning screw passes through the screw plug and is slidably connected to the screw plug front and back, a seal is provided between the smooth rod portion and the sliding contact surface of the screw plug, a warning mark is provided on the cylindrical surface of the smooth rod portion, and the warning mark is located in front of the front end face of the cylinder barrel when the oil returns to the rod chamber.

[0007] The spring is preferably a disc spring.

[0008] An annular groove is provided on the front end surface of the piston, and the rear part of the spring is installed in the annular groove.

[0009] An annular sealing groove is respectively provided on the outer cylindrical surface of the piston and the inner cylindrical surface of the cylinder barrel and the piston rod of the single-rod piston cylinder which slides together. A retaining ring and an O-ring are provided in the sealing groove. The retaining ring on the piston and the retaining ring on the cylinder barrel are respectively in front of and behind the corresponding O-ring.

[0010] The cylinder barrel may include a cylinder body and an end cover fixed at an open front end of the cylinder body, and the screw plug mounting through hole is provided on the end cover.

[0011] In the rod chamber oil return state, the warning mark is preferably 3-5 mm away from the front end surface of the cylinder.

[0012] A coal mining machine braking device with wear detection includes a housing, a rear cover, a spline sleeve, a brake assembly and the disc brake operating mechanism, the housing and the rear cover are both annular disc parts, the cylinder, the housing and the rear cover are arranged in sequence from front to rear and the three are coaxially fixedly connected, a circular groove is provided on the end face of the extended end of the piston rod of the single-rod piston cylinder, the front and rear parts of the spline sleeve are respectively arranged in the circular groove and the central through hole of the rear cover, the spline sleeve and the rear cover are axially and radially positioned by a stopper, and the spline sleeve is restricted from moving backward by a retaining ring installed on the rear cover, the brake assembly includes multiple inner friction plates and multiple outer friction plates, the main bodies of the inner friction plates and the outer friction plates are both annular, the inner and outer friction plates are alternately stacked in the axial direction, and the inner and outer friction plates are coaxial in the radial direction and their respective main bodies remain partially or completely overlapped, The inner edge of the main body of the inner friction plate is provided with a plurality of inner claws extending radially inward, and the outer edge of the main body of the outer friction plate is provided with a plurality of outer claws extending radially outward. The inner hole of the spline sleeve is a spline hole, and the outer cylindrical surface of the spline sleeve is provided with a plurality of axially penetrating external grooves. The inner friction plate is sleeved on the spline sleeve and the inner claws are embedded in the outer grooves one by one and are connected to the corresponding outer grooves for sliding back and forth. The inner cylindrical surface of the outer shell is provided with a plurality of axially penetrating internal grooves. The outer friction plate is installed in the inner hole of the outer shell and the outer claws are embedded in the inner grooves one by one and are connected to the corresponding inner grooves for sliding back and forth. The piston rod and the rear cover respectively limit the brake assembly axially from the front and rear directions. When oil enters the rod cavity, the brake is released, and the adjacent inner and outer friction plates are separated from each other. When oil returns from the rod cavity, the brake is engaged. The main bodies of the adjacent inner and outer friction plates are in close contact and there is no relative rotation.

[0013] The coal mining machine braking device with wear detection adopts a wet working mode. The space enclosed by the piston cylinder, outer shell, rear cover and spline sleeve is a friction chamber. The gap between the inner and outer friction plates and the radial gap between the spline sleeve and the circular groove become a channel connecting the friction chamber and the inner hole of the spline sleeve.

[0014] A wave spring sheet is provided on the radial outer side of the inner friction sheet and between the main bodies of each two adjacent outer friction sheets. The thickness of the wave spring sheet is not greater than that of the inner friction sheet, and the free height of the wave spring sheet is greater than the thickness of the inner friction sheet.

[0015] The beneficial effects of the utility model are:

[0016] The setting of the warning screw can truly reflect the wear condition of the friction plate, making it convenient to grasp the changes in the wear amount of the friction plate at any time underground, and solve the problem of difficult manual detection or large detection errors caused by harsh working environment and installation location, resulting in excessive wear of the inner and outer friction plates not being discovered and corrected in time, leading to insufficient braking torque and even causing safety accidents such as slipping, which greatly facilitates underground maintenance and use.

[0017] The central threaded hole can be used to release the brake mechanically to ensure that the brake can be released reliably when the hydraulic brake system or the brake fails and needs maintenance, and can also be used for oiling during normal use, thus killing two birds with one stone. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a cross-sectional view of an embodiment of the disc brake operating mechanism;

[0019] Figure 2 An end view of an embodiment of the coal mining machine braking device with wear detection;

[0020] Figure 3 for Figure 2 AA rotation section view (brake state);

[0021] Figure 4 for Figure 3 K magnified image;

[0022] Figure 5 for Figure 3 Schematic diagram of the axial structure of the spline sleeve;

[0023] Figure 6 for Figure 3 The assembly diagram of the coal mining machine braking device with wear detection and the high-speed shaft of the traction part transmission system is shown.

[0024] Reference numerals:

[0025] 1. Piston; 2. Cylinder; 3. Spring; 4. Splined sleeve; 5. Housing; 6. Inner friction plate; 7. Outer friction plate; 8. Rear cover; 9. Wave spring plate; 10. Screw plug; 11. End cover; 12. Warning screw; 13. High-speed shaft; 14. First long bolt; 15. Second long bolt. DETAILED DESCRIPTION

[0026] like Figure 1-6As shown, the utility model discloses a disc brake operating mechanism, including a warning screw 12, a plug 10 and a single-rod piston cylinder. The front and rear chambers of the single-rod piston cylinder are a rodless chamber and a rod chamber respectively. A spring 3 is provided in the rodless chamber, and the spring is kept in a compressed state. The rod chamber is connected to a low-pressure hydraulic control circuit. A central threaded hole that passes through the front and back is provided in the middle of the piston of the piston cylinder. A plug mounting hole is provided on the front wall of the cylinder barrel of the piston cylinder. The plug is installed in the plug mounting hole. The rear end of the warning screw is a threaded portion, and the front part is a smooth rod portion. There is a radially outward protruding flange between the threaded portion and the smooth rod portion. In the embodiment shown in the accompanying drawings, the threaded portion adopts an M16 thread. The threaded portion of the warning screw is threadedly connected to the central threaded hole. The flange is used for axial positioning of the warning screw relative to the piston. The maximum screw-in depth of the threaded portion is determined by the flange. The warning screw will move back and forth with the piston. The smooth rod portion of the warning screw passes through the screw plug and is connected to the screw plug in a forward and backward sliding manner. A seal is provided between the sliding contact surface of the smooth rod portion and the screw plug, which can prevent coal slag and water from entering the brake and can also prevent the internal oil of the brake from leaking out. The seal in the accompanying figure is an O-ring, which is arranged in an annular sealing groove opened along the circumferential direction on the cylindrical surface of the smooth rod portion. A warning mark is provided on the cylindrical surface of the smooth rod portion, for example, it can be a dot, a line or a circle mark around the entire circumference set on the cylindrical surface of the smooth rod portion. When the disc brake operating mechanism is used for a disc brake, the piston rod of the single-rod piston cylinder maintains contact with the front end of the brake assembly of the brake under the action of the spring, and the forward and backward movement of the piston rod corresponds to the release and engagement of the brake assembly respectively.

[0027] In the rod chamber oil return state (i.e., brake engagement state), the warning mark is located in front of the front end face of the cylinder barrel. As the inner and outer friction plates wear, the piston will move further and further rearward when the brake is engaged, and the position of the warning mark will also move closer and closer to the cylinder barrel. When the distance between the inner and outer friction plates reaches a certain level, the inner and outer friction plates have reached the maximum allowable wear. At this time, the inner and outer friction plates must be replaced in groups, usually by replacing the brake assembly as a whole. The degree of proximity required to replace the inner and outer friction plates can be determined based on the actual situation. In this embodiment, when the warning mark is found to be sunken into the front end face of the cylinder barrel, it is considered necessary to replace the inner and outer friction plates.

[0028] The setting of the warning screw can truly reflect the wear condition of the friction plate, making it convenient to grasp the changes in the wear amount of the friction plate at any time underground, and solve the problem that manual detection is difficult or the detection error is large due to the harsh working environment and the installation location, resulting in excessive wear of the inner and outer friction plates not being discovered and corrected in time, resulting in insufficient braking torque and even causing safety accidents such as slipping.

[0029] The spring is preferably a disc spring, which has high rigidity, strong buffering and vibration absorption capabilities, can withstand large loads with small deformation, and occupies little axial space, so the braking device can be more compact in the axial direction.

[0030] An annular groove is provided on the front end surface of the piston, and the rear part of the spring is installed in the annular groove. As a part of the spring is embedded in the piston, the axial size of the brake can be further reduced.

[0031] An annular sealing groove is provided on the outer cylindrical surface of the piston and on the inner cylindrical surface of the cylinder barrel, which slides with the piston rod of the single-rod piston cylinder. A retaining ring and an O-ring are provided in the sealing groove. The retaining ring on the piston and the retaining ring on the cylinder barrel are respectively located in front of and behind the corresponding O-ring, that is, both are on the low-pressure side of the corresponding O-ring. Compared with a sealing structure with only an O-ring, the retaining ring can prevent pressurized oil from squeezing the O-ring into the gap between the piston and piston rod and the cylinder barrel, thereby extending the service life of the O-ring. The O-ring is preferably made of fluororubber sealing material, which has better heat resistance, can adapt to high-temperature working environments, and is not easily aged or deformed.

[0032] The cylinder barrel may include a cylinder body 2 and an end cover 11 fixed at the front end opening of the cylinder body, the end cover serving as the front wall of the cylinder barrel. The screw plug installation through hole is provided on the end cover.

[0033] In the rod chamber oil return state, the warning mark is preferably 3-5 mm away from the front end surface of the cylinder, and is 3 mm in the embodiment shown in the drawings, that is, the inner and outer friction plates need to be replaced when the total wear reaches 3 mm.

[0034] The utility model also discloses a coal mining machine braking device with wear detection (which can be simply referred to as a braking device), comprising a housing 5, a rear cover 8, a spline sleeve 4, a brake assembly, and the disc brake operating mechanism. The housing and the rear cover are both annular disc parts, and the cylinder barrel, the housing, and the rear cover are arranged in sequence from front to back and the three are coaxially fixedly connected by passing a first long bolt 14. A circular groove is provided on the end face of the extended end of the piston rod of the single-rod piston cylinder, and the front and rear parts of the spline sleeve are respectively arranged in the circular groove and the central through hole of the rear cover. The spline sleeve and the rear cover are axially and radially positioned by a stopper, and the spline sleeve is restricted from moving backward by a retaining ring installed on the rear cover.

[0035] The brake assembly includes multiple inner friction plates 6 and multiple outer friction plates 7. The inner and outer friction plates are each annular in shape. They are alternately stacked axially and radially coaxial, with their respective plates partially or completely overlapping. The annular disc surfaces of adjacent inner and outer friction plates form a set of friction pairs. The brake device comprises multiple sets of friction pairs.

[0036] The inner edge of the main body of the inner friction plate is provided with multiple (e.g., three) radially inwardly extending inner claws, while the outer edge of the main body of the outer friction plate is provided with multiple (e.g., six) radially outwardly extending outer claws. The inner bore of the splined sleeve is a splined hole, and the outer cylindrical surface of the splined sleeve is provided with multiple axially extending outer grooves. The inner friction plate is mounted on the splined sleeve, and the inner claws fit into the outer grooves one-to-one and are connected to the corresponding outer grooves in a forward and backward sliding manner. The inner cylindrical surface of the outer housing is provided with multiple axially extending inner grooves. The outer friction plate is installed in the inner bore of the outer housing, and the outer claws fit into the inner grooves one-to-one and are connected to the corresponding inner grooves in a forward and backward sliding manner. The outer grooves are used to limit the rotation of the outer friction plate, while the inner grooves are used to synchronize the rotation or stop of the splined sleeve and the inner friction plate. The outer and inner grooves are preferably evenly distributed around their respective axes. The piston rod and rear cover 8 respectively limit the axial position of the brake assembly in the front and rear directions. When oil flows into the rod cavity, the brake is released and the adjacent inner and outer friction plates are separated from each other. When oil returns to the rod cavity, the brake is engaged and the main bodies of the adjacent inner and outer friction plates are in close contact and there is no relative rotation.

[0037] The front and rear ends of the brake assembly are preferably outer friction plates.

[0038] The cylinder 2 and housing 5 can be positioned axially and radially by means of circular stoppers. The housing 5 and rear cover 8 can also be positioned axially and radially by means of circular stoppers. In the accompanying drawings, the housing is a ring without a stopper. The rear end face of the cylinder and the front end face of the rear cover are each provided with a circular outer stopper. Sealing gaskets are provided at the joints between the rear end face of the cylinder and the front end face of the rear cover and the housing.

[0039] The aforementioned coal mining machine brake device with wear detection preferably utilizes a wet operating mode to reduce friction plate wear and prevent sparking. Specifically, the space enclosed by the piston cylinder, housing, rear cover, and splined sleeve forms a friction chamber. The gap between the inner and outer friction plates, as well as the radial gap between the splined sleeve and the circular groove, form a channel connecting the friction chamber and the inner bore of the splined sleeve. The gear oil in the traction housing flows through the gap between the splined sleeve and the high-speed shaft and enters the friction chamber through the aforementioned channel. The gear oil serves as the working oil for the friction plates.

[0040] Furthermore, a wave spring sheet is provided on the radial outer side of the inner friction plate and between the main bodies of each two adjacent outer friction plates. The thickness of the wave spring sheet is not greater than the thickness of the inner friction plate, and the free height of the wave spring sheet is greater than the thickness of the inner friction plate.

[0041] Since the free height of the wave spring sheet is greater than the thickness of the inner friction sheet, once the axial pressure is removed, the wave spring sheet will axially extend to restore the free height, and will bounce the two adjacent outer friction sheets apart to ensure the brake is released.

[0042] The temperature of the coal mining machine braking device is high during operation, especially the local temperature between the friction plates is higher, which may reach more than 100 degrees. The material of the wave spring plate is usually 65Mn, which is not easy to age, deform or even burn out compared with rubber material, and is more reliable in operation and has a longer service life.

[0043] The wave spring is naturally positioned within the annular space formed by the adjacent inner and outer friction plates, resulting in a simple structure and easy assembly. Furthermore, the wave spring's force to open the outer friction plate acts on the outer friction plate from multiple areas evenly distributed across the entire annular plane, ensuring a more uniform axial force on the outer friction plate and preventing tilting or jamming.

[0044] The central threaded hole can be used to inject oil into the friction chamber. This is primarily done in two situations: First, before installation, when the brake device undergoes factory testing; and second, before starting the shearer on a steeply inclined working surface or at a certain angle, it's necessary to check for gear oil flowing into the friction chamber of the brake device on the higher end of the traction unit. If not, oil needs to be injected.

[0045] It is also possible to provide a plurality of through holes extending forward and backward around the central threaded hole on the piston. In the figure, the plurality of through holes are evenly distributed along the circumference. On the one hand, the through holes can also be used for oil injection, thereby speeding up the oil injection speed. On the other hand, when the brake device is as a whole mounted on the gear spline, the friction chamber is a closed chamber, and the through holes can be used for exhaust.

[0046] The central threaded hole can also be used to mechanically release the brake. To do this, first remove the screw plug 10, place a flat washer on the front end of the cylinder barrel or end cap, and thread an M16 bolt through the washer into the central threaded hole of the piston until the bolt head rests on the washer. Continue tightening the bolt, and the piston will lift, releasing the brake. This convenient and reliable method can be used to release the brake when a hydraulic brake system or brake device malfunctions and requires repair.

[0047] The front and back mentioned in this article correspond to Figure 1 、 3 Left and right in the perspective are for the convenience of expression, not for limiting the absolute direction.

[0048] A coal mining machine is equipped with two brake devices, which are respectively installed at the left and right traction shafts (i.e. the high-speed shaft 13 of the traction part transmission system) of the coal mining machine (see Figure 6), specifically, the external spline at the end of the high-speed shaft is spline-connected with the internal spline on the spline sleeve. During installation, first put the entire brake device on the high-speed shaft gear spline, and then use 12 second-long bolts 15 to fix it to the traction part housing. In order to avoid accidentally removing the first long bolt when removing the brake device as a whole, mark the head of the first long bolt. In the parking state, there is oil return to the rod chamber, and the piston 1 of the piston cylinder moves backward under the thrust of the spring 3. The axial pressure of the spring 3 presses the inner and outer friction plates against each other through the piston, and the brake is engaged. In the engaged state, the adjacent inner and outer friction plates are in close contact and there is no relative rotation. The spline sleeve is also stationary relative to the outer shell with the inner friction plate, applying a braking torque to the high-speed shaft, and the wave spring plate is axially compressed between the outer friction plates. Since the spring force of the wave spring plate is very small, it does not affect the braking torque. When the coal mining machine is ready to start moving, oil enters the rod chamber, and the piston 1 moves forward under the action of liquid pressure to overcome the spring force of spring 3, causing the axial pressure between the adjacent inner and outer friction plates to be pressed against each other to be cancelled, the brake device is released, and the spline sleeve drives the inner friction plate to rotate relative to the outer shell, thus not affecting the rotation of the high-speed shaft.

Claims

1. A disc brake operating mechanism, characterized in that: It includes a warning screw, a screw plug and a single-rod piston cylinder, the front and rear chambers of the single-rod piston cylinder are respectively a rodless chamber and a rod chamber, a spring is provided in the rodless chamber, the spring is kept in a compressed state, the rod chamber is connected to the hydraulic control circuit, the middle part of the piston of the piston cylinder is provided with a central threaded hole that passes through the front and back, and a screw plug mounting through hole is provided on the front side wall of the cylinder barrel of the piston cylinder, the screw plug is installed in the screw plug mounting through hole, the rear end part of the warning screw is a threaded part, and the front part is a smooth rod part, and a radially outward protruding flange is between the threaded part and the smooth rod part, the threaded part of the warning screw is threadedly connected to the central threaded hole, and the flange is used for axial positioning of the warning screw relative to the piston, the smooth rod part of the warning screw passes through the screw plug and is connected to the screw plug for sliding back and forth, a seal is provided between the smooth rod part and the sliding contact surface of the screw plug, and a warning mark is provided on the cylindrical surface of the smooth rod part, and the warning mark is located in front of the front end face of the cylinder barrel when the oil returns to the rod chamber.

2. The disc brake operating mechanism according to claim 1, wherein: The spring is a disc spring.

3. The disc brake operating mechanism according to claim 1, wherein: An annular groove is provided on the front end surface of the piston, and the rear part of the spring is installed in the annular groove.

4. The disc brake operating mechanism according to claim 1, wherein: An annular sealing groove is respectively provided on the outer cylindrical surface of the piston and the inner cylindrical surface of the cylinder barrel and the piston rod of the single-rod piston cylinder which slides together. A retaining ring and an O-ring are provided in the sealing groove. The retaining ring on the piston and the retaining ring on the cylinder barrel are respectively in front of and behind the corresponding O-ring.

5. The disc brake operating mechanism according to claim 1, wherein: The cylinder barrel comprises a cylinder body and an end cover fixed at an open front end of the cylinder body, and the screw plug mounting through hole is arranged on the end cover.

6. A disc brake operating mechanism according to claim 1, 2, 3, 4 or 5, characterized in that: When the oil returns from the rod chamber, the warning mark is 3-5 mm away from the front end surface of the cylinder.

7. A coal mining machine braking device with wear detection, characterized in that: The invention comprises a housing, a rear cover, a spline sleeve, a brake assembly and a disc brake operating mechanism as described in claim 1, 2, 3, 4, 5 or 6, wherein the housing and the rear cover are both annular disc parts, the cylinder, the housing and the rear cover are arranged in sequence from front to rear and the three are coaxially fixedly connected, a circular groove is provided on the end face of the extended end of the piston rod of the single-rod piston cylinder, the front and rear parts of the spline sleeve are respectively arranged in the circular groove and the central through hole of the rear cover, the spline sleeve and the rear cover are axially and radially positioned by a stopper, and the spline sleeve is restricted from moving backward by a retaining ring installed on the rear cover, the brake assembly comprises a plurality of inner friction plates and a plurality of outer friction plates, the main bodies of the inner friction plates and the outer friction plates are both annular, the inner and outer friction plates are alternately stacked in the axial direction, and the inner and outer friction plates are coaxial in the radial direction and their respective main bodies remain partially or completely overlapped, The inner edge of the main body of the inner friction plate is provided with a plurality of inner claws extending radially inward, and the outer edge of the main body of the outer friction plate is provided with a plurality of outer claws extending radially outward. The inner hole of the spline sleeve is a spline hole, and the outer cylindrical surface of the spline sleeve is provided with a plurality of axially penetrating external grooves. The inner friction plate is sleeved on the spline sleeve and the inner claws are embedded in the outer grooves one by one and are connected to the corresponding outer grooves for sliding back and forth. The inner cylindrical surface of the outer shell is provided with a plurality of axially penetrating internal grooves. The outer friction plate is installed in the inner hole of the outer shell and the outer claws are embedded in the inner grooves one by one and are connected to the corresponding inner grooves for sliding back and forth. The piston rod and the rear cover respectively limit the brake assembly axially from the front and rear directions. When oil enters the rod cavity, the brake is released, and the adjacent inner and outer friction plates are separated from each other. When oil returns from the rod cavity, the brake is engaged. The main bodies of the adjacent inner and outer friction plates are in close contact and there is no relative rotation.

8. The coal mining machine braking device with wear detection according to claim 7, characterized in that: It adopts a wet working mode. The space enclosed by the piston cylinder, outer shell, rear cover and spline sleeve is the friction chamber. The gap between the inner and outer friction plates and the radial gap between the spline sleeve and the circular groove become the channel connecting the friction chamber and the inner hole of the spline sleeve.

9. The coal mining machine braking device with wear detection according to claim 7 or 8, characterized in that: A wave spring sheet is provided on the radial outer side of the inner friction sheet and between the main bodies of each two adjacent outer friction sheets. The thickness of the wave spring sheet is not greater than that of the inner friction sheet, and the free height of the wave spring sheet is greater than the thickness of the inner friction sheet.

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