Designing an Improved Structure of the Tool for Repairing the Brake Pipe Connectors in Vehicles

This paper addresses the issue of difficulties in servicing the brake pipe connectors for passenger cars, the service life of which exceeds 8‒10 years, which is associated with the deteriorated loosening of connectors. The existing ways to loosen the connectors of brake pipes have been investigated, especially those whose dismantling is complicated due to the corrosion and contamination of mated surfaces as a result of their wetting when driving a car. A conventional structure of the connector has been analyzed, which is installed in that place of the car that is the most unprotected from moisture and dirt – on the brake cylinder. The conditions that do not contribute to its failure-free loosening have been examined. The design of a specialized split clamping ring wrench has been considered, which can transmit the greatest value of the torque to the connector when loosening it; sometimes, however, its predefined value would not suffice. A computer-based finite-element simulation was employed to derive the models of the deformation state for the node «connector ‒ wrench». Based on the analysis of the models of different deformation state of a specialized split clamping ring wrench, the required profile of the geometrically balanced locked hexagonal profile of the wrench was defined. The analysis of the efficiency of the tightening and loosening level is determined by comparing the numerical values of the torque, which is applied to the connectors of the brake pipes. The torque values are measured by a specially devised technique. The introduction of the developed measurement technique makes it possible to compare the efficiency of wrenches of different designs by analyzing the maximum values of torques, which the wrenches can transmit to the connectors. Taking into consideration the identified shortcomings in the structure of the brake pipe connectors, the shape of the connector has been designed that is free from the specified drawbacks. The new structure provides for the possibility of using a conventional carob wrench for loosening when the mated surfaces are exposed to contamination and corrosio

Improving the Abrasive Resistance of a Slide Frame in a Mortar Mixer

A method has been proposed for machining the outer and inner conical surfaces of the wrist pin and insert, which represent a sliding friction pair on the mortar mixer frame. The machining implies the application on the conical surface of parts, preliminary prepared through turning, of a wear-resistant material in the form of a hard alloyed nickel-based powder. It is applied with a special burner with a hopper-dispenser filled with powder. The result of mixing a combustible gas (acetylene and oxygen) in the burner with the powder from the hopper is melting.In the course of implementing a given technological process, by using mathematical modeling methods, we have determined the optimal mode parameters (PG10N-01 powder consumption is 33.5 g/min.; oxygen flow rate is 7.0 l/min; acetylene pressure is 0.043 MPa) for the gas-flame surfacing, which ensured maximum effect, that is, the greatest strength of adhesion (45 MPa) for the surfaced coating. The surfaced coating quality was checked by using a pin method for determining the adhesion strength between the new coating and the base on a tensile testing machine.A series of experimental studies into the enhancement of abrasive resistance of a sliding frame, namely a comparison of the surfaced coating with other well-known wear-resistant materials such as steel ShKh15, KhVG, were carried out at a specially designed experimental bench. Its structure is based on a vertically drilling desktop machine adjusted to the conditions of a working process that occurs inside the body of a mortar mixer. These include an abrasive medium, and the radial and axial efforts. To determine the axial load on a frame, we have proposed a structure of the hydraulic device, which includes a pressure gauge, a piston, a sleeve, and a ball. The axial load has been found for the most unfavorable conditions of mixer operation. Its value was implemented at an experimental wear bench. In addition, we have performed a series of experimental studies to determine an optimum angle of the cone at the apex of the wrist pin and insert in a conical slide frame for the minimal wear.Using the proposed technique of a gas-flame surfacing could significantly improve the abrasive and corrosion resistance of a slide frame, thereby prolonging the lifespan of a mortar mixer in general, as well as the overhaul cycle for equipment designed to prepare soluble mixtures used for constructio