RU2144458C1 - Method of and device for removing passenger car brake drum - Google Patents

Abstract

FIELD: mechanical engineering; maintenance and repair of passenger car drum-type brake systems. SUBSTANCE: to remove brake drum from axle-shaft use is made of device whose housing has threaded hole in which power threaded member is installed. Grips are mounted on housing, and axle-shaft stop is installed coaxially with treaded member. Support with compensators is coupled with stop to provide coaxial alignment of device and axle-shaft. Housing is provided with pressure flats for clamping the drum and is furnished pins with tensioners to apply radial forces to drum holes. Housing rotates together with treaded power member relative to stop. The latter has end piece for fixing the stop in shaped recess on end face of axle shaft and bead. Using pins of device, radial balancing forces are applied to surfaces of hole in drum wall to provided elastic expansion of seat hole. Forces acting along axle-shaft are applied to axle-shaft and drum end face. In process of application of forces, drum is turned relative to axle-shaft to provide their axial alignment. EFFECT: increased capacity and quality of demounting of brake drum. 3 cl, 2 dwg

Description

 The invention relates to instrumental equipment and is applicable for maintenance of brake systems of a drum type of a car, as well as for removing parts such as thin disks of low stiffness with an undeveloped hub, but having holes near the hub.

 The closest analogue of the proposed method is given in (1) on page 196, Fig. 155 c, d, in which forces are directed in opposite directions to the axle shaft and the end of the drum located on it using a gripping device with a threaded power element.

 When using this method, grabs are applied to the end of the shell of the drum and the threaded force element to the center of the axle shaft balanced and symmetrical at the first moment, but unstable system of forces directed parallel to the axis of the shaft. The forces from the puller grips, gathering in their resultant on the surface of the hub, due to the low stiffness of the drum wall and the large distance of the grippers from the hub, produce a significant deformation of the drum wall in the form of complex spatial bending, which leads to the clamping of the hub on the axle shaft.

 The instability of the system of forces pushes even a slight random skew and asymmetry of forces to an avalanche-like development, which leads to jamming. The process of jamming and clamping is aggravated by the presence of additional forces of “sticking” of the hub to the shaft from accumulated corrosion products on the seating surfaces.

 Under these conditions, a further increase in axial forces leads to even greater deformations and even destruction of the drum. This is the reason that grippers with a threaded force element are not used for maintenance of passenger car braking systems.

 The proposed method is aimed at minimizing the frictional forces between the seating surfaces of the drum and the axle shaft by mechanical means and creating conditions that prevent the development of the deformation of the drum wall, clamping and jamming when axial forces are applied to the drum and the axle shaft.

 To reduce friction forces, a radially directed and mutually balanced forces are applied to the wall of the drum in its plane, elastically expanding the landing hole of the drum. These efforts are transmitted from the device’s body on the surface of the holes intended for passage of the wheel mounting bolts through cylindrical fingers pivotally mounted on the device. The friction forces between the surfaces of the holes and fingers that occur when radial forces are applied act in the same direction as the forces from the grippers applied to the end face of the drum and reduce their sum by the amount of their sum. This decrease, depending on the friction conditions, can be significant, reducing the forces from the grips to zero, thereby preventing deformation of the drum wall, clamping the drum hub on the axle shaft and an increase in the friction forces between them, depending on the magnitude of the forces applied to the end of the drum.

 Thus, the application of radial forces not only prevents the growth of resistance forces to remove the drum, but also provides some reduction as a result of elastic expansion of the landing hole.

 This is followed by the second stage of reducing friction forces by replacing the resting friction forces by the friction forces of movement of the drum by rotation around the axle shaft. Sometimes it is possible to overcome very significant forces of rest friction and “sticking” by applying a sufficient moment of rotation applied through the device’s body to the drum fixed on its pressure pads. The semi-axis reactive moment is transmitted through the stopper and then through the support to the garage floor in the form of a pair of support reaction forces. This stopper and support also ensure alignment of the device with the axle shaft during the removal of the drum, which prevents jamming. The rotation of the drum, carried out simultaneously with the application of axial and radial forces, provides energized conditions for the friction of the movement of the hub on the axle shaft, which significantly reduces the axial force required to remove the drum.

 The drawing shows the proposed device.

 The device consists of a housing 1 with a threaded hole, in which there is a threaded power element 2, coaxially with which the axle stopper 3 is located, having a shoulder for stopping the force element and a tip 11 for fixing it in the shaped end of the axle shaft. Fingers 4 with tensioners 5 are mounted on the housing, it has platforms 6 for pressing the drum with grippers 7 in terms of the number of grippers, but not less than two, and also a torque receiver 8 from the operator’s means. The grips have threaded power elements for clamping the drum to the device body. The stopper is movably connected to a support 9 having threaded expansion joints for transmitting reactive torque to the garage floor through a threaded lock 10 located on the support.

 When installing the device on the drum, the stopper tip is introduced into the center of the axle shaft, the fingers are inserted into the holes, the drum is pressed to the pressure pads of the housing with grippers, the support with compensators is installed on the garage floor and the stopper is fixed. When removing the drum with the help of tensioners, radial forces are transferred to the drum wall and the friction forces are fixed on the fingers of the drum wall, the axial force is created by the force element, and at the same time, the assembly moment creates the moment of rotation through the pipe receiver and rotates the drum.

 Experience shows that eating even a very “sticky” drum does not cause difficulties and requires a few minutes. The elastic deformation of the bore hole with a not very tight tightening of the “key” threaded tensioners for the VAZ-2101 drum is 0.01 + 0.012 mm without visible removal of the surface of the holes.

 The hydraulic drive of the tensioners will allow the use of a device with a very high productivity.

Sources of information:
1. Semenov V.M. Non-standard tool for dismantling and assembly work. -M .: Agropromizdat, 1985, p. 196.

Claims (3)

 1. A method of removing a brake drum of a passenger car, in which a force is applied to the axle shaft and the end of the drum having openings in the wall using a gripping device with a threaded force element, characterized in that fingers are applied to the surfaces of the openings in the drum wall the devices apply radial balancing forces from the condition of providing elastic expansion of the landing hole of the drum with the inclusion of forces arising between the surfaces of the holes and fingers friction in the sum of the forces applied by the device along the semiaxis to the drum, and in the process of applying forces, the drum is rotated relative to the semiaxis, while ensuring their alignment.  2. A device for removing a brake drum of a passenger car, comprising a housing with a threaded hole in which a threaded power element is mounted, drum end grips mounted on the housing, characterized in that it is provided with a half-axle stopper arranged coaxially with the threaded force element to interact with the latter for transmitting axial force to the axle shaft during rotation of the power element, bearing with compensators associated with the stopper and ensuring alignment of the device with the axle shaft on the floor g razha and fixing the stopper with a threaded lock, fingers that are equipped with tensioners for applying radial forces to the holes of the drum, the housing is made with clamping pads for clamping the drum between the grippers and the housing, for which the grippers are made with threaded force elements, mounted for rotation together with the threaded power an element relative to the stopper and is equipped with a receiver for means transmitting rotation from the operator to the housing; the stopper is made with a tip for fixing it in the end uosi shaped recess and a shoulder, and a threaded element power is set to cooperate with said end face of its flange.  3. The device according to claim 2, characterized in that it is equipped with hydraulic cylinders associated with finger tensioners to create forces on them.