Seamless Rotary Guidance System: Bishop-Wisecarver 1-Trak Part I

© 2013 | All Rights Reserved | www.bwc.com
Motion Without Limits ®
Introducing PRT2 1-Trak: Part I of III
A Seamless Ring and Track Guided Motion System

OUTLINE OF OVERVIEW — PART I OF III
Original PRT2 Systems
New 1-Trak Systems
Any Shape, Any Size
Four Bearing Carriage
Three Bearing Carriage
Track Geometry
Rectangular Section Track System
Contact Information

ORIGINAL PRT2 TRACK SYSTEMS
The PRT2 precision ring and track offering is one of
BWC’s most popular motion guidance solutions
Includes broad range of sizes and component types
Market leading products
However, in some instances the traditional PRT2
offering did not meet certain specifications

NEW! PRT2 1-TRAK
1-Trak extends the capability of PRT2
Patent pending design with three key innovations:
Create almost any 2D shape of track in one piece
(within the maximum size limits and minimum bend radii)
Three-bearing geometry allows a carriage to run around any
2D shape of track
Available with or without gear drive

WE CAN MAKE ANY SHAPE
A new manufacturing method for creating rings has been
developed since 2011:
Parts are made using special steel, are precision machined,
and surface hardened
This route gives high surface hardness and very low distortion
Applicable for all sizes (from miniatures to huge HD parts)

ANY SHAPE, ANY SIZE
Ring is much thinner for this diameter than can be
manufactured using the traditional approach

Hyperbolic shape
Assembly is Ø4.4 m
Made in smaller pieces and butted together
ANY SHAPE, ANY SIZE

ANY SHAPE, ANY SIZE
Our CAM software
provides for the ability to
make unusual and
complex components
We can create a PRT2
track in one piece

ANY SHAPE, ANY SIZE
Tracks can be made to include an integral base plate
No installation or adjustment
Can be major structural element of machine

ANY OF THESE STYLES ARE POSSIBLE

CREATE ANY SHAPE
The steel has a high tensile strength, more than
900MPa: stronger than a standard 8.8 hex socket screw
This gives indentation resistance beyond the max load
capacity of all compatible vee bearings
Surface hardened to > 600HV (~ 55HRC+)
Case depth is ~0.2mm
Great wear resistance
(proper lubrication is essential for long life)
The finish is precision machined, producing a great
running surface

FOUR BEARING CARRIAGE GEOMETRY
Four Bearing Fixed Centre Carriage
The lift-off increases as:
Segment diameter reduces
Track width increases
Bearing separations increase
This limits the proportions of useful track systems

FOUR BEARING CARRIAGE GEOMETRY

THREE BEARING CARRIAGE GEOMETRY

As two bearings on the outside roll around the track,
the inside vee bearing will follow a unique path
The 1-Trak approach calculates this unique shape,
and machines it accurately into the inside of the track

The width of the track is constantly changed depending
upon its bend radius
In this example, dimensions A, B, C, and D are different
A dedicated CAM system automatically creates the track
geometry to very high precision

Our manufacturing approach can accurately produce
finished components with close tolerances on
straightness, flatness, and shape
Within 0.002” flatness in the free state

Carriage uses three off SJ25 bearings: Load capacity <<
four bearing carriage — center of load capacity is offset
Section based on NS25 (like 25 section PRT2 rings)
Pitch (MP), Yaw (MY), and Roll (MR) moment load
capacities are modest compared to FCC25 255

Carriage uses one SJ18 on the inside and two SJ13’s on
the outside: the load capacity is broadly symmetrical
Track section and spacing of bearings is wide
Carriage Roll (MR) moment load capacity is high, despite
the tight bend radius
Integral base plate is a very strong/stiff structural element

Different sized bearings and an asymmetrical track
profile will produce a carriage with even load capacity
The larger bearing is taller, but this does not cause a
problem for systems which are hollow in the middle

TRACK GEOMETRY
Virtually any smooth 2D shape can be made into a
1-Trak system, providing that the bearing radii and
separation will allow the carriage to go round
Free-form curves are no problem

TRACK GEOMETRY
Tracks can be open or closed shapes

RECTANGULAR SECTION TRACK SYSTEM
1-Track construction can be used to make tracks with
a “flat track” floating function for use in parallel
mounted systems

RECTANGULAR SECTION TRACK SYSTEM
1-Trak approach gives flexibility to make rectangular
section tracks (similar function to PRT2 floating bearings)
Floating bearings can be used with vee profiled 1-Trak
Rollers will give lower friction, better track life and lower cost
Tracks designed for 4-bearing carriages to operate in
parallel with standard PRT2 track systems with FCC
carriages are possible

CONTINUED…
Be sure to view part II of III in the 1-Trak overview
series for more information on:
Driving By Gears
Available on the Bishop-Wisecarver’s SlideShare:
(www.slideshare.net/bishopwisecarver)

THANK YOU
Have questions? Please contact…
An Applications Engineer at (888) 580.8272
Or email info@bwc.com
Learn more on our website at www.bwc.com

Seamless Rotary Guidance System: Bishop-Wisecarver 1-Trak Part I

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