Preload and Retraction Device of a Wheel Assembly and Self-Propelled Cart Comprising Said Device

Abstract

A preload and retraction device (10, 10′) of a wheel assembly comprises a linear guide (11), an internal slider (12) and an external slider (13) movable along the linear guide (11), a linear elastic member (14) arranged to connect the two sliders (12) (13), a first wheel support arm (15) integral with the internal slider (12) and a second wheel support arm (19) integral with the external slider (13), with the external slider (13) carrying a weight support wheel (20) that is actuated and the internal slider (12) carrying a traction wheel (16) that comes into contact with a rolling surface with a preload force that is a function of the geometry of the system. The use of the device (10, 10′) is particularly advantageous for supporting the wheels in a self-propelled cart (100) of the type suitable for moving along a railway track for the inspection of the underbody of railway vehicles as it greatly facilitates and at least partially automates the installation of the self-propelled cart (100) on the track.

1 .- 8 . (canceled) 
     
     
         9 . A preload and retraction device of a wheel assembly, comprising:
 a linear guide;   an internal slider freely movable along the linear guide;   an external slider movable in controlled mode along the linear guide;   an elastic member, arranged to connect the internal slider and external slider to each other so as to hinder relative movements of moving away or approaching the internal slider and the external slider with respect to a defined natural length distance;   a first wheel support arm integral with the internal slider, extending substantially in the direction of the linear guide and suitable for supporting at least a first wheel in rotatable mode around a relative first axis with a rolling direction of the at least a first wheel substantially orthogonal to the direction of the linear guide; and   a second wheel support arm integral with the external slider extending substantially in the direction of the linear guide and suitable for supporting at least a second wheel in rotatable mode around a related second axis with a rolling direction of the at least a second wheel parallel to the rolling direction of the at least a first wheel.   
     
     
         10 . The preload and retraction device of a wheel assembly according to  claim 9 , further comprising preload adjustment members interposed between the elastic member and at least one between the external slider and the internal slider to adjust the distance between the internal slider and the external slider in the natural length condition of the elastic member. 
     
     
         11 . The preload and retraction device of a wheel assembly according to  claim 9 , further comprising drive members integral with at least one of the first wheel support arm and the second wheel support arm to rotate at least one of the supported wheels thereof. 
     
     
         12 . The preload and retraction device of a wheel assembly according to  claim 11 , wherein the drive members are integral with the first wheel support arm to rotate the first wheel and it comprises an electric motor, a pulley or toothed wheel coaxial and integral with the first wheel and a transmission belt between the pulley or toothed wheel and the drive shaft of the electric motor. 
     
     
         13 . A self-propelled cart of the type suitable for moving in confined spaces between two substantially facing guide surfaces, comprising:
 a platform; and   support and movement means on wheels;   wherein the support and movement means on wheels comprises at least two preload and retraction devices of a wheel assembly thereof, the preload and retraction devices being mounted on the specular way with respect to a longitudinal axis of the platform defining a direction of advancement of the platform ( 30 ) itself, each of the preload and retraction devices comprising:   a linear guide anchored to the platform so as to extend in the plane of the platform in a direction substantially orthogonal to the aforementioned direction of advancement of the self-propelled cart;   an internal slider freely movable along the linear guide;   an external slider movable in a controlled mode along the linear guide:   an elastic member, arranged to connect the internal slider and external slider to each other so as to hinder relative movements of moving away or approaching the internal slider and the external slider with respect to a defined natural length distance;   a first wheel support arm integral with the internal slider, extending substantially in the direction of the linear guide and suitable for supporting at least a first wheel in rotatable mode around a relative first axis with a rolling direction of the at least a first wheel substantially orthogonal to the direction of the linear guide and parallel to the longitudinal axis;   a second wheel support arm integral with the external slider, extending substantially in the direction of the linear guide and suitable for supporting at least a second wheel in rotatable mode around a related second axis with a rolling direction of the at least a second wheel parallel to that of the at least a first wheel;   drive members integral with at least one of the first wheel support arm and second wheel support arm to rotate at least one of the supported wheels thereof.   
     
     
         14 . The self-propelled cart according to  claim 13 , wherein the at least a first wheel has its first wheel axis substantially orthogonal to the plane identified by the platform and is provided with the drive members so that the at least a first wheel can be rotated to move ahead or back the self-propelled cart. 
     
     
         15 . The self-propelled cart according to  claim 13 , wherein the at least a second wheel has its second wheel axis substantially parallel to the direction of extension of the linear guide, so that the at least a second wheel is arranged substantially vertically to support a weight of the self-propelled cart. 
     
     
         16 . The self-propelled cart according to  claim 15 , of the type suitable for moving along a railway track for the inspection of an underbody of railway vehicles, wherein the platform has a maximum transverse dimension, with reference to the direction of longitudinal axis and therefore to the direction of advancement of the self-propelled cart along a railway track, smaller than a size of a gauge of the rails that form the railway track, the at least a first wheel and at least a second wheel being arranged externally to the platform with respect to the transverse direction in such a way that following the actuation of the external slider along the linear guide the at least a first wheel and at least a second wheel selectively assume different operating configurations, among which at least one of: (a) a retracted configuration with minimum transverse dimensions of the self-propelled cart in which the at least one first wheel and at least a second wheel are both detached from the surfaces of the rail; (b) an intermediate first contact configuration, in which the at least a first wheel comes into contact with the internal surface of a stem of a rail while the at least a second wheel is detached from the rail; or (c) an extracted working configuration, in which the at least a first wheel is in contact with the internal surface of the stem of the rail with a determined contact force and the at least one second wheel is in contact with a rail foot upper plane of the rail, the drive members being integral with the first wheel support arm to rotate the at least a first wheel while the at least a second wheel is arranged to roll freely conducted on the rail foot upper plane of the rail, the overall vertical dimensions of the self-propelled cart being substantially contained in the overall dimensions in height of the rail so that the self-propelled cart is able to move along the track below the track rolling surface.