FIELD OF INVENTION
This invention relates to high energy capacity side buffers for use in rolling stocks and capable of performing a first function of a normal buffering action and a second function of absorbing energy caused by an accident or crash.
PRIOR ART
Buffers for use with a rolling are known in the art. One such buffer is disclosed in WO 2805/115815, and which is capable of performing both of the aforesaid first and second functions. Such a buffer comprises a buffer casing held to one end of a rolling stock through a flange. The buffer further comprises a plunger having a sleeve held to an integral protection tube through a shear plate said tube disposed within said casing. A hollow shaft extends from the flange, a elastomeric pad embracing said shaft.
Thus, during a normal buffering, the force is transferred to the elastomeric pad through the head of the plunger. However, during a crash function, there is a load build up at the shear plate, which cracks and allows the sleeve
of the plunger to telescopically slide over the protection tube resulting in a peeling effect. As described, a shear plate connects the sleeve of the plunger to the inner tube, and it is only upon breaking of the shear plate that allows the performance of the second function.
OBJECTS OF THE INVENTION
An object of this invention is to propose an improved construction of a crash buffer for a rolling stock and capable of performing a first function of a normal buffering and a second function of absorbing the energy caused by an accident or crash.
Another object of this invention is to propose an improved construction of a crash buffer for a rolling stock and capable of performing a first function of a normal buffering and a second function of absorbing the energy caused by an accident, and for said second function a crash plate is no longer employed.
Still another object of this invention is to propose an improved construction of a crash buffer for a rolling stock and capable of performing a first function of a normal buffering and a second function of
absorbing the energy caused by an accident or crash which has a simple construction.
Yet another object of this invention is to propose an improved construction of a crash buffer for a rolling stock and capable of performing a first function of a normal buffering and a second function of absorbing the energy caused by an accident or crash which is efficient.
Further objects and advantages of this invention will be more apparent from the ensuing description.
STATEMENT OF INVENTION
According to this invention there is provided high energy capacity side buffers for use in rolling stocks and capable of performing a first function of a normal buffering action and a second function of absorbing energy caused by an accident or crash comprising :
a. a flange adapted to be held to one end of a rolling stock
b. said flange extending into an outer casing
c. a plunger at the opposite end of said outer casing
d. a slide tube within said housing and adopted to be displaced
towards and upto the flange in the presence of the first
function
e. a resilient means disposed within said outer casing
characterized in that
f. a crash tube is disposed within said outer casing and held to
the inner face of said plunger.
g. said crash tube extending upto the head of a slide tube and
coacting therewith and adapted to displace the slide tube
towards the flange and transfer the force to the flange so as
to allow a peeling effect in the presence of the second
function.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings and wherein:
Fig. 1 shows: Top and Sectional view of side buffer of the present invention.
Fig. 2 shows: Exploded view of the side buffer.
Fig. 3 shows: Crash tube assembly of the present invention.
Fig. 4 shows: Banana peeling effect.
Fig. 5 shows: position of the stack with respect to outer casing tube.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS
Reference may be made to the accompanying drawings wherein a crash tube (2) is provided inside the outer casing (7). The tube (2) is held to the inner face of said plunger (1). The crash tube extends upto the head of a slide tube (4) and coacting therewith. It is adapted to move the slide tube towards the flange and transfer the force to the flange so as to allow a peeling effect in the presence of second function as shown in fig4.
Principle of working
The basic functioning of buffer can be divided into 2 main zones.
• The elastic zone/normal buffer zone/reversible stroke.
• Plastic zone/crash zone.
The buffer is mounted on the end wall of the rolling stock through the flange which is integral with the outer casing.
A plunger (1), crash tube (2) and slide tube (4) are free to slide inside the outer casing (7).
Elastic Zone/Reversible Stroke
When force is applied at the plunger, the load gets transferred from plunger (1) to the slide tube (4) through the Crash Tube (2). The resilient means such as elastic spring column 6 starts to experience load as it is sandwiched between the stack of plunger (1), crash tube (2), slide tube (4) and outer casing (7). The resilient means (6) starts to deflect after the pre load on it is over come. At this position, the stack of plunger (1), crash tube (2) and slide tube (4) starts moving telescopically into outer
casing till the base of slide tube sits on the face of outer casing. During this travel of the stack, the resilient means gets progressively compressed and hence the reaction load experienced at the interface of the vehicle and buffer is increased.
This can be explained from the chart below.
(Table Removed)
Plot - Buffer Energizing
Where T = Travel of plunger stack telescopically in the outer casing in mm.
RL = Reactive load experienced at the interface of the buffer and the end wall of the vehicle in (kN). This load is opposite in direction to the applied load on the plunger stack.
P = Pre load of the elastic spring in (kN)
Now reference may be made to fig. 5 upon the release of load, the plunger stack reverts back to its original position. In doing so, it absorbs energy as can be explained in the chart below :

(Table Removed)
Plot - Buffer Reversed Stroke
Where LC = Loading curve
UC = Unloading curve EL = Typical end force.
The area under the curve is the energy absorbed during the buffer stroke which is approx. 60KJ. The above explanation is for the working principle during the buffing zone.
The Damping Factor in the static mode is for example 0.5 and the Damping Factor in the Dynamic mode is for example 0.6
The maximum end force at the end of travel in buffing mode will not exceed for example 750 kN in a static condition.
Crash Zone
In case of an accident or severe hit of the rolling stock when the load increases beyond the typical end load builds up. The crash tube (2) and outer casing (7) start to deform axially and banana peel respectively.
This deformation allows further travel of plunger (1) with respect to outer casing (7) beyond the elastic stroke. This stroke is called as plastic stroke as no elastic stroke is possible after this. As this deformation proceeds, a
Center Guide (5) travels the distance between the open side of center guide (5) and Conical Lug on the back face of the plunger (1) and at the end of the plastic stroke, the open end of the centre guide splits so as to lock the resilient means.
It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims:-

WE CLAIM:
1. High energy capacity side buffers for use in rolling stocks and capable of performing a first function of a normal buffering action and a second function of absorbing energy caused by an accident or crash comprising :
a. a flange adapted to be held to one end of a rolling stock
b. said flange extending into an outer casing
c. a plunger at the opposite end of said outer casing
d. a slide tube within said housing and adopted to be displaced
towards and upto the flange in the presence of the first
function
e. a resilient means disposed within said outer casing
characterized in that
f. a crash tube is disposed within said outer casing and held to
the inner face of said plunger.
g. said crash tube extending upto the head of a slide tube and
coacting therewith and adapted to displace the slide tube
towards the flange and transfer the force to the flange so as
to allow a peeling effect in the presence of the second
function.
2. High energy capacity side buffers for use in rolling stocks and capable of performing a first function of a normal buffering action and a second function of absorbing energy caused by an accident or crash substantially as herein described with reference to the accompanying drawings.