Rail tie plate placing vehicle and method

A railroad tie plate placing vehicle uses a crawler track to place plates upon rail ties. The crawler track is meshed to a magnetic wheel which holds tie plates to the crawler track until the tie plates have actually contacted a tie. The crawler track at least partially propels the vehicle down the railroad track when the vehicle is placing plates. A tie detector switch is used to control gates which gate tie plates onto the conveyor and magnetic wheel upon detection of a tie such that a tie plate released by the gates will reach a release point in the closed loop of the conveyor at the same time as the release point reaches the tie whose detection triggered the gating of the tie plate.

BACKGROUND OF THE INVENTION 
This invention relates to a tie plate placing vehicle and associated method 
of placing tie plates. 
When laying a new railroad track or when laying new rails upon a previously 
existing railroad track, it is necessary to provide tie plates upon the 
railroad ties. One tie plate is required for each side of each tie and 
typically more than three thousand tie plates would be required for one 
mile of track. 
The tie plates may be manually placed upon each of the ties after the tie 
plates have been placed in piles along side the track. Typically, the tie 
plates are distributed by a crane having a magnetic head which drops piles 
of tie plates along side the track. The distance between the piles depends 
upon the average number of tie plates carried by the magnetic head of the 
crane. A work gang of about 10 to 15 persons would take tie plates from 
the pile and properly position them upon the railroad ties. Considering 
that the tie plates weigh about 28 pounds each and that the tie plates 
should be placed in the proper position on the tie, it will be appreciated 
that this method of placement involves high labor costs, inconsistent 
accuracy of placement, and a time consuming process. 
Various machines have been developed in an attempt to avoid the manual 
method of tie plate placement. In particular, U.S. Pat. No. 3,943,858 
issued to Dieringer et al on Mar. 16, 1976 and U.S. Pat. No. 4,241,663 
issued to Lund et al on Dec. 30, 1980 show such machines. 
The Dieringer et al patent shows a tie plate placement arrangement using a 
finger for sensing tie position. Upon detection of a tie, the machine is 
designed to stop over each tie and operate gating fingers to drop each tie 
plate upon the corresponding tie. A track mechanism may be used to support 
one side of the vehicle and a conveyor belt arrangement is used for 
conveying tie plates on the machine. 
The Lund et al patent shows an arrangement in which tie plates are placed 
upon ties by a device including a chute. Tie plates are gated into the 
chute and an electromagnet is used to hold a tie plate in position such 
that it will be properly dropped over a tie as determined by a limit 
switch which is tripped by contact of a tie detector with a tie. 
There have been a number of problems associated with various of the prior 
art methods and devices for distribution of tie plates along ties. 
The manual method of tie plate distribution is subject to high labor costs, 
inconsistent accuracy of placement, and relative slow speed of tie plate 
distribution, whereas the prior machines for tie plate distribution are 
often subject to the last two disadvantages. More specifically, the 
machines often rely upon dropping of tie plates onto the tie such that the 
placement accuracy is limited by this factor. Additionally, machines which 
must stop in order to drop or place a tie plate are generally slow in 
placing tie plates along a given stretch of railroad track, whereas plate 
placing machines which drop the ties while the machine is moving are often 
subject to greater inaccuracy. 
Various of the prior art plate placing machines have been quite complex in 
construction and, therefore, relatively expensive. 
Prior placer machines which require electro magnets typically require 
relatively high power electric energy sources. 
OBJECTS AND SUMMARY OF THE INVENTION 
Accordingly, it is a primary object of the present invention to provide a 
new and improved rail tie plate placing vehicle. 
Another object of the present invention is to provide a new and improved 
tie plate placing method. 
A more specific object of the present invention is to provide tie plate 
placement in a relatively speedy fashion. 
A further object of the present invention is to provide relatively accurate 
placement of tie plates. 
A still further object of the present invention is to provide tie plate 
placement at a relatively low operational cost and with relatively low 
labor cost. 
Objects of the present invention also include overcoming or minimizing the 
problems common with prior art plate placement techniques. These and other 
objects which will become more apparent from the following are realized by 
a rail tie plate placing vehicle comprising: a main frame; a moving 
conveyor extending in a closed loop, the conveyor supported by the main 
frame and operable in a plate placing mode to place tie plates upon ties 
of a railroad track as the vehicle moves down the railroad track; a first 
gate for gating the conveyance of tie plates by the conveyor, the first 
gate disposable in a blocking state wherein it blocks the conveyance of a 
leading tie plate and disposable in an open state wherein it allows 
passage of a leading tie plate for conveyance by movement of the conveyor; 
holding means for holding tie plates against the conveyor and allowing the 
release of tie plates at a common predetermined release point of the 
closed loop for immediate disposal upon a tie; and a tie detector 
supported by the main frame for detection of ties at a detection point 
forward of the release point; and wherein the tie detector causes the 
first gate to open for passage of a tie plate corresponding to the 
detection of a tie, and wherein the conveyor is operable such that the tie 
plate allowed passage by the first gate arrives at the release point when 
the vehicle has moved the release point over the detected tie. Preferably, 
the conveyor is operable to propel the vehicle along a track. The conveyor 
is disposed to contact ties along the track and the weight of the vehicle 
causes tie plates to stop moving with the vehicle such that each tie plate 
is deposited upon a tie. The conveyor is preferably a crawler track. The 
conveyor is a flexible conveyor having a plate conveying surface with an 
upwardly facing portion, a downwardly facing portion, and a transitional 
portion between the upwardly facing portion and the downwardly facing 
portion. The invention further comprises holding means cooperating with 
the conveyor for holding tie plates against the transitional and 
downwardly facing portions of the plate conveying surface and for 
releasing tie plates at the release point which is located at the 
downwardly facing portion. The vehicle further comprises a magnetic wheel 
rotating upon movement of the conveyor. The holding means comprises a 
plurality of permanent magnets mounted to the magnetic wheel. The tie 
detector is a switch mounted for accuation by ties. The distance from the 
first gate to the release point is equal to the distance from the 
detection point to the release point. The tie detector causes the first 
gate to assume its open state immediately upon detection of a tie. A plate 
detector detects a tie plate at a place on the conveyor downstream of the 
first gate and causes the first gate to assume its blocking state prior to 
complete passage of a leading tie plate past the first gate such that the 
leading tie plate moves with the conveyor, but any following tie plate is 
blocked. The first gate is mounted adjacent a first side of the conveyor. 
A second gate is mounted adjacent a second side of a conveyor and operable 
in like fashion with the first gate for simultaneously gating tie plates 
by joint action of the first and second gates. 
The invention may alternately be described as a rail tie plate placing 
vehicle comprising: a main frame; a moving closed loop flexible conveyor 
supported by the main frame and operable in a plate placing mode to place 
tie plates upon ties of a railroad track, and wherein the conveyor 
includes a plate conveying surface having an upwardly facing portion, a 
downwardly facing portion, and a transitional portion between the upwardly 
facing portion and the downwardly facing portion; and holding means 
cooperating with the conveyor for holding tie plates against the 
transitional and downwardly facing portions of the plate conveying surface 
and releasing tie plates at a release point from the downwardly facing 
portion for placement upon ties. The vehicle may further comprise an 
inclined conveying means having a plate placement surface adapted to 
receive tie plates thereon for movement to a lower end of the conveying 
means, and wherein the lower end terminates above the conveyor such that 
tie plates placed on the conveying means are deposited upon the conveyor. 
The method of the present invention may be described as a method of placing 
tie plates upon ties from a tie plate placing vehicle, the steps 
comprising: moving the vehicle along a railroad track; detecting ties on 
the railroad track; gating a tie plate by way of a first gate for movement 
with a closed loop, moving conveyor for each detected tie; moving each 
gated tie plate to a release point on a conveyor such that the gated tie 
plate is at the release point when the vehicle has moved sufficiently that 
the release point is immediately over the detected tie whose detection 
caused the gating of that gated tie plate; and releasing each gated tie 
plate when it arrives at the release point. Preferably, the tie plate is 
gated for movement with the conveyor upon the detection of a tie. The 
conveyor is moving at the same speed as the vehicle. The method further 
comprises the step of propelling the vehicle by movement of the conveyor. 
The vehicle is moving during the releasing step. The conveyor is a crawler 
track which contacts the railroad track and the releasing step results 
from the weight of the vehicle causing tie plates to stop moving with the 
vehicle such that each tie plate is deposited upon a tie. The method 
further comprises the steps of detecting plates at a place on the conveyor 
downstream of the first gate and causing the first to assume a blocking 
state upon detection of a plate. The method further comprises the step of 
holding tie plates to the conveyor by permanent magnets in a magnetic 
wheel which rotates upon movement of the conveyor. The releasing step 
occurs upon a tie plate contacting a tie, while the tie plate is still in 
contact with the conveyor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Initially considering the side view of FIG. 1 and the top view of FIG. 2, 
the general structure of the plate placing vehicle 10 of the present 
invention will be discussed. The vehicle 10 includes a main frame 12 and 
four wheels arranged in a front pair 14FR and 14FL and a back pair 14BR 
and a back left wheel (not visible in the drawings but in a symmetric 
postion as the right wheel 14BR). The four wheels support the vehicle 10 
for movement along a railroad track having two rails. The frame 12 may 
also include parts which extend between the front pair of wheels and the 
back pair of wheels. 
The front of the vehicle 10 includes an engine 16, hydraulic oil tanks 18, 
pumps 20, a fuel tank 22, a battery 24, and an air tank 26. Mounted at the 
back of the vehicle 10 is storage bin 28 into which tie plates may be 
placed. Although the vehicle 10 might include a crane or other arrangement 
to place tie plates within the bin 28, this is not a necessary part of the 
present invention. 
A center platform 30 extends lengthwise along the center of the vehicle, 
whereas a side platform 32 extends along the left side of the vehicle 10. 
The platform 30 and 32 provide a space where one or more persons may stand 
during operation of the vehicle 10. 
Continuing to view FIGS. 1 and 2, but also considering the cross sections 
views of FIGS. 3 and 6 respectively taken along lines 3--3 and 6--6 of 
FIG. 1, the construction of a placer assembly 34 will be described. It is 
the placer assembly 34 which functions to place tie plates upon the tie 
during operation of the vehicle 10. 
The placer assembly 34 includes a frame structure 36. This placer frame 36 
includes right and left members 38R and 38L which extend lengthwise 
completely along the placer assembly 34. Additionally, the members 38R and 
38L allow the placer assembly 34 to be secured to either side of the 
vehicle 10. Although various arrangements could be used, the illustrated 
arrangement has lower pieces 40 mounted on the bottom of the members 38R 
and 38L. The lower pieces 40 are bifurcated so as to have a channel which 
accommodates mounting pieces 42, which mounting pieces 42 are vertical 
strips secured to the frame of the vehicle itself. There are four of the 
mounting pieces 42 upon each side of the vehicle (see especially FIG. 2) 
such that the side platform 32 may be interchanged with the placer 
assembly 34 depending upon which side of the track tie plates are required 
to be placed. The mounting pieces 42 have lower stops 44 which prevent the 
placer assembly 34 from falling below the level shown in FIG. 1. 
Additionally, the mounting pieces 42 include 3 holes 46. Each of the holes 
46 may receive a locking pin (not shown) which would secure the placer 
assembly 34 in different positions. That is, the lower hole 46 may be 
pinned when the placer assembly 34 is in the position shown in FIG. 1 such 
that the lower pieces 40 would be captured between the pin corresponding 
to lower hole 46 and the stops 44. When the vehicle 10 is moving along a 
section of track which does not need tie plates placement and which has 
two rails, the placer assembly 34 may be moved upwardly by removing the 
pins in the lower holes 46, attaching a crane or otherwise lifting the 
placer assembly 34 by way of upper members 48 (FIG. 1 only), which upper 
members are secured to the placer frame 36. When the lower pieces 40 are 
disposed between the two upper locking holes 46 within the vertical strip 
mounting pieces 42, locking pins may be placed in the two upper holes 46 
for each of the pieces 42, thereby capturing the lower pieces 40 
therebetween to secure the placer assembly 34 in an upper or inoperative 
position. 
An optional platform 50 (FIG. 2 only) may be secured to the placer frame 36 
to allow a person to stand thereon for loading tie plates from the bin 28 
onto the placer assembly 34. 
The placer frame 36 further includes front and back transverse members 52F 
and 52B extending between the side members 38R and 38L. The transverse 
members 52F and 52B support lengthwise extending upper and lower members 
54U and 54W. The lower member 54W is supported from front and back plates 
66F and 66B. As best shown in FIG. 6, the upper member 54U has a track bar 
56 to accommodate rollers of a chain roller type conveyor 58. The lower 
member 54W includes a member 60 having rollers 62 mounted thereon for 
cooperation with the conveyor 58. 
As best shown in FIG. 1, the conveyor 58 extends in a closed loop 
longitudinally along the placer assembly 34. The conveyor 58 is flexible 
in that, like a conveyor belt, it includes portions which may flex or move 
relative to other portions. For example, the conveyor 58 is preferably a 
crawler track with a plurality of links connected together for relative 
pivoting therebetween. A possible configuration for the conveyor 58 is 
shown in FIG. 6, but other configurations could of course be used. The 
conveyor 58 is a moving conveyor in that it moves articles by movement of 
the conveyor itself. The conveyor 58 is generally perpendicular to the 
ties 64. 
Mounted at the back of the crawler assembly 34 is a crawler drive motor 68 
and a drive sprocket for causing the conveyor 58 to move in a clockwise 
(FIG. 1 view) direction. 
Considering now FIGS. 1 and 3 in conjunction with the FIG. 5 cross 
sectional view taken along lines 5--5 of FIG. 3, a magnetic wheel 70 is 
mounted for rotation upon a shaft 72 extending between the members 38R and 
38L. The magnetic wheel 70 includes a sprocket 74 meshed to the conveyor 
58 and symmetric arrangements of permanent magnets 76 on each side of the 
sprocket 74. The magnets 76 may be arranged in 8 sets of magnets, 3 
magnets in each set, for each side of the sprocket 74. The magnets 76 are 
held between an 8-sided inner ring 78 and a circular outer ring 80. There 
is one inner ring 78 and outer ring 80 for each side of the sprocket 74. 
The magnets 76 are arranged to form a series circuit also extending through 
a pair of outer disks 82, which are made of magnetic metal to serve as 
pole pieces in establishing a magnetic circuit through a tie plate 84 as 
illustrated at the top of FIG. 3. The outer ring 80 is preferably made of 
stainless steel to minimize the effects of the magnets 76 upon the 
conveyor 58 itself. 
Pneumatic cylinder gates 86 (FIGS. 1, 3, and 4) are mounted upon brackets 
88 and used for gating tie plates onto the conveyor 58. A plate detect 
microswitch 90 is mounted upon one of the brackets 88. With reference to 
FIGS. 1, 2, and 4, a roller conveyor 92 having rollers 94 may serve as a 
conveying means for feeding tie plates onto the lower conveyor 58. The 
roller conveyor 92 is mounted upon support members 96 extending from the 
placer assembly frame 36. Although the pneumatic cylinder gates 86 are 
mechanical blocking gates, the term "gates" as used herein shall include 
any means which may alternately "open" (i.e., allow passage) to allow 
movement of an article and "block" (i.e., prevent passage) to restrain 
against movement. For example, a suction conduit could be used as a gate 
to control the flow of tie plates onto conveyor 58. Tie plates may procede 
down the roller conveyor 92 to the crawler track conveyor 58 and be 
deposited thereon adjacent the gates 86. 
In order to properly position the tie plates 84 upon the conveyor 58, a tie 
plate width accommodation mechanism 98 is shown in FIGS. 1, 4, 7, and 8. 
To adjust for different distances between the ridges of tie plates, the 
mechanism 98 includes two finger members 100A and 100B which are pivotably 
connected together at pivot point 102. A support member 104, which is a 
frame for the roller conveyor 92, may include slots 106A and 106B to 
accommodate different positions of the fingers 100A and 100B. 
Specifically, the solid line position of FIG. 8 shows the mechanism 98 
adjusted for a tie plate having a shorter distance between its ridges. The 
fingers 100A and 100B are respectfully bolted in position by bolts 108A 
and 108B extending through the slots 106A and 106B and into the underside 
of the finger members 100A and 100B. The bolts 108A and 108B could extend 
up from the bottom of the slots 106A and 106B into holes on the underside 
of the fingers 100A and 100B or, alternately, could be mounted in 
countersunk holes upon the top of the finger members 100A and 100B. 
From the solid line position of the finger members 100A and 100B in FIG. 8, 
the mechanism 98 may be adjusted to accommodate tie plates having greater 
width between their ridges by removing the bolts 108A and 108B and 
pivoting the finger members 100A and 100B outwardly to assume the phantom 
line positions of FIG. 8, whereupon the bolts 108A and 108B are used to 
secure the fingers in their outer positions. In either the narrow solid 
line position of FIG. 8 or the wide phantom line position of FIG. 8, the 
fingers 100A and 100B have the illustrated shape such that the conveyor 58 
may pass between the tips of the fingers and the fingers insure that the 
tie plates are properly positioned upon the conveyor 58. 
With reference to FIGS. 1 and 9, a tie detector microswitch 110 is mounted 
upon a skid comprising a channel member 112 and a T member 114. The 
channel member 112 is pivotably mounted at pivot point 116 attached to a 
downwardly projecting member 117 of the placer frame 36. The member 114 
may be adjusted for longitudinal position relative to channel member 112 
by virtue of front and back pairs of holes 118 (only one hole visible in 
FIG. 9) through which front and back pairs of bolts 120 (only one bolt 
shown in FIG. 9) may extend. The member 114 may be slid forward or 
backward by loosing the front and back pair of bolts 120. The bolts 120 
may then be retightened to secure the member 114 to the channel member 
112. A limit chain 140 prevents the skid from pivoting so far down that 
the skid might jam the machine against forward movement. 
The tie detector switch 110 is preferably positioned such that the detect 
point (the point at which its switch arm extends for detection of a tie) 
is spaced from a release point 122 (FIG. 1, a point at which tie plates 
upon conveyor 58 are placed upon a tie 64) equal to the distance (i.e., 
around the conveyor 58) from the gates 86 to the release point 122. The 
significance of this relationship in distances will be better understood 
when the operation of the invention is discussed below. 
When the vehicle 10 has moved along a pair of rails by way of its wheels 
14FR, 14FL, 14BR, 14BL until it reaches a point whereat plate placing is 
required, there will be only one rail on which the vehicle 10 may ride. 
Accordingly, a gauging wheel arrangement such as shown in FIG. 10 may be 
used. In particular, a support plate 124 is pivotably mounted at pivot 
point 126 fixed to the frame of the vehicle 10. The support plate 124 is 
pressed downwardly by a member 128 in order to bias a roller 130 against 
the rail 132. The link 128 may have an air brake chamber (not shown) 
attached to its top to press downwardly on the plate 124 and bias the 
roller 130 so as to capture the rail 132 between the roller 130 and the 
wheel 14FL. A similar arrangement would be used at the back wheel such 
that the vehicle 10 may proceed upon a single rail. 
Before leaving a double rail area of track and after the gauging wheels or 
rollers 130 have been properly positioned, two of the four outriggers 123 
will be extended so as to support one side of the vehicle 10. In 
particular, the outriggers 123 would be extended to support the side of 
the vehicle 10 on which the plate placer is mounted such that the plate 
placer 34 may then be lowered from an upper position captured between the 
upper holes 46 and a lower position, shown in FIG. 1. Before the plate 
placer 34 is lowered, the vehicle 10 should have its left side wheels upon 
a rail and the back right side wheel upon a rail whereas the front right 
wheel will not be in contact with a rail, but the right side outriggers 
123 will be extended. Upon lowering the plate placer 34 and securing it in 
position, the outrigger jacks 123 may be retracted and the vehicle 10 may 
proceed by virtue of propulsion and support by the crawler track 58 in 
addition to having the opposite side supported and propelled by the back 
left wheel. It will thus be appreciated that at the crawler track conveyor 
58 applies at least a portion of the weight of the vehicle to the ties by 
way of the tie plates. 
As shown by the simplified schematic of FIG. 11, the hydraulic pump 20 
feeds hydraulic oil to a rear axle drive motor 134 in parallel to the 
motor 68 which drives the crawler or conveyor 58 by way of sprocket 68S. 
By hooking up the motors 134 and 68 in parallel in the hydraulic circuit, 
the motors are in effect geared to the ground and will run at an 
appropriate speed to stay in synchronization with each other. This avoids 
possible slippage which might otherwise occur if the motor 134 and 68 
operated at different speeds. 
With reference to FIG. 12, a simplified electric and pneumatic arrangement 
for the present invention is shown. The battery 26 is connected to a 
solenoid coil 136 by way of the normally open tie detector switch 110 and 
the normally closed plate detector switch 90. The solenoid 136 controls a 
valve 138 which connects pressurized air and exhaust conduits to the 
parallel connection of the pneumatic gates 86. 
Operation 
As the vehicle 10 proceeds along a railroad track under the power of the 
crawler track conveyor 58 in addition to one of its rear wheels upon a 
rail, the tie detector switch 110 will be closed for each tie which is 
detected. One or more persons on the various platforms of the vehicle may 
be removing tie plates from the bin 28 and placing them upon the roller 
conveying means 92, the mechanism 98 having been set for the tie plates 
which are to be placed. The tie plates will stack up in a line behind 
(i.e., to the left in FIGS. 1 and 4) the gates 86. 
Upon the tie detector 110 detecting a tie 64, the closing of the switch 110 
(FIG. 12) will switch the valve 138 to reverse the flow of air to gates 86 
and cause the retraction of the pneumatic gates 86 to a retracted position 
shown as 86R in FIG. 4. A tie plate 84 may then easily pass over the gates 
86 moving with the conveyor 58 and fixed to the magnetic wheel 70 by the 
permanent magnets 76 (FIG. 3). When the tie plate 84 contacts the switch 
arm of plate detect switch 90, it opens the switch 90, causing the valve 
138 to return the gates 86 to their extended position. By placing the 
plate detect switch 90 closer to the gate 86 then the length of the tie 
plates 84, the gates 86 will resume their extended or blocking state and 
push up on the tie plate 84 as illustrated in FIG. 4. However, the plate 
will have sufficiently cleared the gates 86 such that it may continue 
around from the upwardly facing portion of the plate conveying surface of 
conveyor 58 to the transitional or sideway facing portion of the conveyor 
58. The tie plate 84 may freely pass by the switch arm plate detect switch 
90. By causing the gates 86 to resume their blocking state before a 
leading (i.e., at the front of the line at gates 86) tie plate 84 has 
completely passed the gates 86, the arrangement ensures that only a single 
plate may pass for each tie detected by the tie detect switch 110. By the 
time the tie plate has cleared plate switch 90 such that the switch 90 
recloses, the tie detect switch 110 will have cleared the tie and 
reopened. Therefore, the gates 86 will not reopen until the switch 110 
detects the next tie. 
As shown in FIG. 1, the tie plates 84 may proceed along the conveyor 58 and 
magnetic wheel 70, the permanent magnets of which serve as a holding means 
to secure the tie plates 84 against the conveyor 58 as the plate conveying 
or outer surface of the conveyor 58 curves from its upwardingly facing 
portion to a downwardly facing portion adjacent the release point 122. 
When a tie plate 84 reaches the release point 122, this corresponds to the 
tie plate 84 hitting a tie 64 and being deposited thereon. The tie plate 
84 is placed on the tie and released in the sense that it no longer moves 
with the vehicle 10, but instead is stationary relative to the ground and 
ties 64. The weight of the vehicle 10 upon the tie plate 84 ensures that 
it will not move. Additionally, as the movement of the crawler track 58 is 
at the same speed as the movement of the vehicle 10, the portion of 
crawler track 58 which is contacting deposited ties is not moving 
horizontally with respect to the tie plates which have already been 
placed. Instead, the tie plates 84 will remain stationary with respect to 
the conveyor 58 until the vehicle has moved sufficiently forward that the 
conveyor portion immediately above the placed tie plate is lifted off the 
tie plate by the drive motor 68. The weight of the vehicle 10 and the 
position of the conveyor 58 prevents the tie plates 84 from moving back 
upwardly around the magnetic wheel 70 such that the tie plate 84 is 
"released" from the holding means of magnets 76 within the magnetic wheel 
70. 
For each closing of the tie detect switch 110, a tie plate 84 will be 
released by the gates 86. It is preferable to have the gates 86 open 
immediately upon (i.e., with only the very slight lag inherent in the 
response time of the FIG. 12 arrangement) tie detection, but the use of 
additional delays is also possible. The advantage of having the detect 
point of tie detector 110 at the same tie plate path distance from the 
release point 122 as the distance between the gates 86 and release points 
122 (i.e., meaning the distance traveled by a tie plate as it travels from 
gates 86 to point 122) is that this arrangement will provide proper tie 
plate placement independent of variations in speed because the time of 
travel of a tie plate from the gates 86 to the release point 122 should be 
equal to the time required by the vehicle 10 to move sufficiently that the 
release point 122 is disposed immediately above tie 64 whose detection 
triggered the gating of the particular tie plate. 
Although various specific constructions have been discussed and shown 
herein, these are for illustrative purposes only. Various adaptations and 
modifications will be apparent to those of skill in the art. For example, 
the preferred embodiment uses a magnetic wheel and a flexible conveyor 
such as a crawler track, but alternate versions of the invention (in its 
broad aspects) might be realized by using only the magnetic wheel or only 
the flexible conveyor as a plate placing closed loop conveyor. 
Accordingly, the scope of the present invention should be determined by 
reference to the claims appended hereto.