CA1173467A - Low profile weighing device for railway cars - Google Patents

Abstract

ABSTRACT:
A low height or profile weighing device for railway cars consisting of a series of mobile axle capturing and weighing carriages each incorporating precision load cells.
The carriages are picked up by each wheel pair (axle) as the rail car enters the scale area; when all car axles are on carriages the output from all load cells is electronic-ally summed to yield the car weight. The compact carriage system rides on a near surface concrete slab which rests on an insulation blanket; this obviates the need of a massive foundation going below the frost line but assures no frost heaving or loss of soil bearing capacity during spring break-up.

Description

~7~;7 This lnvention relates to a method of cons-truction of a low hei~ht or profile track scale for accurate static weighing of railway cars.
It is well known that weighing of rail cars can be accompLished by means of 2 relatively long beams located under -the rails and in turn moun~ted on load cells~ Modern high capaci-ty 100 ton cars require approximately 3 feet deep beams if -the number of load cells is kept reasonably small. The conse~uences are that no-t only do we have an expensive scale bridge simply by virtue of the large amount of steel required, but we need a pit foundation to house this rather massive structure. Once a pit requirement is es-tablished one mus~t provide access for service people f'or cleanout, sump ~ump, drainage connections, heating, light-1~ ing, etc. resulting in a very costly structure particular-ly when built by conventional techniques with its footings below the fros-t line.
Attempts have been made to devise low heigh-t or pro-file track scales by using short, multiple platforms (hence shallow beams) of approximately 12 feet length and locating them only under the rail car supporting bogies or -trucks.
The problem is that if only 2 such scale platforms are used (one under each car bogie) the range of car lengths -tha-t the scale is useful for is very restrictive making such a

2~ scale unacceptable for general purpose weighing. If more platforms or weighing elements are ad~ed to extend the use-fully weighable car length range, the cost of the sys-tem rapidly approaches the conventional track scale referred to earlier.
It is the object of this invention to provide a comp-letely different approach to accurate rail car weighing ,~,~

3~

which ~liminates the need for any platform beams, uses a small mlmber of costly load cells and yet can accomodate all car lengths. Furthermore the proposed sys-tem can be constructed within a foo-t of the top of rail elevation allowing us the possibili-ty of uslng a simple concrete slab foundation. Since rail cars normally weighed, like hopper cars, all ha,ve 4 axles it follows that all that is required are 4 axle weigh sta-tions, Now axle spacing with-in a bogie vary a few inches and bogie spacing on various cars can differ by as much as 30 feet, By using moveable weigh carriages according to -this invention all variations are taken care of. As the rail car is pulled (or pushed) on to the scale area its axles one by one pick up a weigh-ing carriage until all 4 axles are on board. The carriages are arranged side by side at the end from which the car approaches the scale. The purpose of the first 3 is -to ac-comodate axle spacing variations, the fourth could be sta-tionary but would lead to an undesirable precise vehicle spotting problem. The fact that the axle "falls into" a well defined capture point on -the carriage enables us to design a very rugged yet relatively compact mobile weigh-ing assembly. This in turn leads to a simple concre-te slab near the surface to support the carriages. By using a "blan-ket" of construction grade thermal insulation the founda-tion 2~ is not only inexpensive but is unaffected by ~rost action such as winter heave and spring soil bearing capacity red-uction.
Referring now to the drawings wherein like reference numbers indicate like parts in the various views:
Fig. l is a plan view of the track scale area showing the 4 weigh carriages or elements.

~7~ 7 ~ig. 2 is a sec-tion of -the line I - I of Fig. 1.
Fig. 3 is a composi-te sec-tional view of Fig. 2 with the left hand side showing section II - II and the right hand side showing the end view III - III.
Fig. 1 shows a plan view of the weighing area which consists of a concrete foundation slab 11 wi-th its top sur-face at about the same level as the normal rail ties 12, The approach rails 13 from each end rest on -the ends of the foundation slab by means of steel spacers 14. The area lQi between the ends of the approach rails 13 constitutes the ~scale~ proper, normally about 72 feet in length. Here we have 2 guide and safety rails 15 spaced up from the slab by chairs 16 so that they are aligned to the same elevat-ion as ~the approach rails 13. Inboard of rails 15 are guid-ed tracks l~ fo~ the~weigh~ca~Eiageæ.18, Fig, 2 shows a - sectionalf.~aide,view~of ~ ,Thei~Q~andat.ion~sl~b 11 is poured directly on top of the insulating thermal blanket 19 which in turn rests on a well compacted subgrade 20 of crushed stone or clean gravel. Fig. 3 is a sectional and end view of Fig. 2 and shows the carriage details. Each carriage has 4 wheels 21 on 2 shafts 22 tied together by 2 rugged steel crossbeams 23. The hardened pin 24 reacts against the load cell 25 providlng a well defined support system for the live load frame 26. Each pair of rail car wheels 28 ride up the wear plate 27 and at the carriage centreline the wheel becomes fixed relati~e to -the carriage which now moves along with the rail car. The wheel ~capture"
by the carriage is effected by a V depression in the wear plate centre as well as assistance from an acti~e electro-magnet 29. The axle weigh-t is transferred from the live f~ame 2G through the load cells 25 to -the crossbeams 23, ;7 wheels 21 and founda-tion slab 11. '~hen the L~ axles are on weigh carriages elec-tronic summation o~ al:L load cells sig-nals gives us an accurate gross vehicle weight. Each carr-iage has an electrical cable and take up reel so that load cell excita-tion, output signal as well as elec-tromagnet excitation can be connected to a stationary controller in the scale house. Besides the electromagnets 29 used by each carriage to engage -the rail car wheels, elec-tromagnetic brakes 30 are mounted near the carriage bottom to anchor carriages whose -turn has not come up to engage passing rail car wheels. The procedure is to have all carriages lined up at car en-try end with brake electromagnets ac-tivated and wheel capture electromagnets 29 deactivated. When one wish-es to place a car on the scale for weighing he simply swit-ches the brake magnet off and the capture magnet on foreach carriage one a-t a time beginning with the inside unit.
This can be done automa-tically with the assistance of limit switches or photocell light beams.
Although the invention has been described with refer-ence to a specific embodiment a number of details may be changed without altering ~he basic concept. To engage a weight carriage with the rail car wheels a solenoid operat-ed mechanical arm could be used or perhaps a small perman-ent magnet could be used with a suitably contoured wear 2~ plate. Indeed i~ the car entry speed is well controlled the system may work with a properly contoured wear plate alone. The load cells need not be shear beam t~pe but ca~
be straight compression units or the carriage~;framework itsel~ could be stain gauge instrumen-ted.

Claims (6)

The embodiment of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A vehicle weighing arrangement comprising of a plurality of mechanically independent, mobile, load sensor equipped weighing carriages numbering one for each axle of the vehicle to be weighed; the said carriages ride on their own separate track and have a means of latching on to the wheels of the vehicle to be weighed, one by one, as said vehicle enters the weighing area; the signals from all sen-sors are summed and converted to weight indication by known means.

2. A weighing arrangement as claimed in 1 wherein the carriages are equipped with contoured wear ramps consisting of a slight incline for the wheels of the vehicle to be weighed so as to have the said wheels run up on to the car-riage as the wheels of the vehicle to be weighed pass over the carriage; the wear ramps have the same incline from each direction with a central V notch where the said vehicle wheels become latched (to a carriage) and have their weights entirely transferred to sensor equipped carriages.

3. A weighing arrangement as claimed in 1 or 2 wherein the carriages are further equipped with electromagnetic clamps to latch or assist in latching a carriage to a desired passing wheel of a vehicle to be weighed.

4. A weighing arrangement as claimed in 1 or 2 wherein the weighing carriages are equipped with electromagnetic clamps to act as brakes so as to anchor or leave stationary carriages being passed over whose turn has not come up to latch on to a particular desired wheel; electromagnetic cl-amps have active elements (the energized coil) and the pas-sive elements (reaction plate) and either can be carriage mounted with the mating element-stationary on the ground.

5. A weighing arrangement as claimed in 1 or 2 where-in the carriages are equipped with mechanical arms control-led either by electrical solenoids or mechanical cams; said arms are used to positively latch carriages on to the wheels of the vehicle to be weighed.

6. A weighing arrangement as claimed in 1 or 2 where-in the track of the sensor equipped weigh carriages rests on a foundation which in turn has underneath it a thermal insulating blanket to control the frost line and hence min-imize winter heaving and loss of soil bearing capacity as-sociated with spring break-up.