Liberty Massive Mini
10/12/2013
For Inspiration and Recognition of Science and Technology
Rex Brown
Team Driven #1730
Lee’s Summit High School
Mentor
rbrown1309@gmail.com
Agenda
 Synchronous Belts
(Thanks to Gates
Belt for Slides)
 Drive Trains
(Thanks to Madison
Krass & Fred Sayre)
 Q&A
Gates Rubber Synchronous Belt Drives
FIRST Robotics Applications
FIRST Robotics Competition – 2008/2009
Gates Rubber Synchronous Belts
Benefits for First Robotics Competition
Gates PowerGrip® GT®2 5MM belts are ideally sized for drives and
functional applications on a FIRST robot
 Lightweight – much lighter than chain and gearing systems for comparable
loads
 Useful – PowerGrip rubber belt drive systems are ideal not only for drives,
but also for linear motion, lifts, game object conveying, positioning, and even
for precisely flinging objects
 Easy to Work With – aluminum sprockets are easy to machine and belting
can be wrapped, cemented, or riveted to structure
 Clean – these drives remain clean because oil is not needed and present a
complete image of current technology
 Quiet – reduced noise as compared with other belt drive technology such as
chain and gears
Tooth Profiles
Gates Synchronous Belts
PG Timing, Trapezoidal,
Gilmer
HTD
TwinPower Timing
(Also available in PowerGrip GT2)
Gates GT, GT2
Materials Supplied in 2007
Power GT2 Belts
Aluminum HTD Sprockets
– Why not GT2 Sprockets
Synchronous Belt Drives
For Comparison Purposes, Let’s give HTD a rated capacity of 1.0 when
operating with HTD sprockets
Typical Belt and Sprocket Profile for HTD
Synchronous Belt Drives
During the mid 1990’s, Gates replaced the PowerGrip HTD belt with PowerGrip GT belts,
and continued running with HTD sprockets.
Typical PowerGrip GT belt in HTD spkt
Synchronous Belt Drives
PowerGrip GT2 Drive System
Typical PowerGrip GT2 belt and sprocket profile
Application Notes
Handling the Belts – Do not bend belts smaller than
the diameter of the 15 groove sprocket.
A one time tight bend or crimp will break the belt’s
fiberglass tensile member and cause loss of strength and
failure of the belt.
Belts can not be joined or spliced by any means other
than grooved splice plates with a minimum 6 teeth.
Drive Alignment - Sprockets must be aligned and shafts
parallel in both planes.
OK!
No Way!
Sprocket Flanges – Provide Flanges either
on both sides of one sprocket or one side on
the driver and the opposite side on the driven
sprocket. All belts drive to one side of the
sprocket. You must use flanges.
Guarding & Debris protection – A
piece of flat plastic supported in
between the belt spans is a simple
way to eliminate pinch points and
keep debris out of the drive.
Application Notes
Belt Tensioning – Tension the belt so that when the drive is under full anticipated load (including shock loads) the belt does not
get slack on one side, or the belt teeth try to climb out of the sprocket grooves. Light load – light pre tension; Heavy load – higher
pre-tension. Make sure the mounting structure does not deflect when either tensioning the belt or under operating conditions. If
you loose tension, the belt will jump teeth. Keep belt shafts parallel and sprockets in line with each other.
Max “climbout” under load
Too little tension or
pulley mounting needs
more structure
Belt Wrap – Minimum of 6 belt teeth fully in mesh &
(60°) belt wrap on the circumference of each sprocket.
This will allow a properly tensioned belt to perform at
100% of its load rating. A backside idler can be useful for
both tensioning the drive and increasing belt wrap. The
idler is used on the slack side of a belt drive. Reversing
drive – Idler on either side.
Product Ratings – Gates belt ratings are set to
guarantee long life on industrial applications.
For FIRST applications, your load capability is
going to be determined by the shaft to sprocket
connections, belt wrap, and the ability to
pretension the drive so that the belt does not
jump teeth. With adequate belt wrap & proper
installation tension, you will be surprised by the
durability of this product! Load capability of the
09 and 15MM width belts is proportional to their
width.
Best advice – One test is
worth a 1000 calculations.
Typical 6-Wheel Synchronous Drive
Notes:
•CIM motor primary drive uses 9MM wide belt. Higher
torque load on wheel drives uses 15MM wide belt. Front
wheel would be 9 or 15 wide depending on loading.
•Rule of Thumb: If using belts for speed reduction, use
narrower belts on higher speeds (usually coming from the
motor) and wider belts at the lower speeds (powering the
wheels)
•Note use of sprocket flanges and belt tensioning points.
•Provide adequate structure to maintain parallel shafts,
sprocket alignment, and ability to maintain tension under
load.
•Total drive ratio is 7.9 : 1
Telescoping Lift with door motor & 5mm Long Length Belting
Application Notes
1.25” diameter flat rollers with a flange can be used for idlers
(either side of the belt.)
Make an easy end connection – for 5mm pitch, 9mmwide
belting long length belting, make a ferrule from ½ diameter x
.035 x 1” Al or Cu tubing. Wrap belting around min. ½”
diameter cylinder (to avoid belt cord damage) and insert belt
loose ends through ferrule. Crimp the ferrule in a vise. Don’t
crimp too tight and you will have a removable connection.
Belt Tensioning – note adjustment screws
Need a reversing drive? PowerGrip Twin Power®
belts have teeth on both driving surfaces.
Robotics Belt Applications
2 stage, 13:1 ratio positioning drive.
Small sprocket on inside of belt span
drives a position feedback pot.
Ball Pitching using opposing belts and a PowerGrip
Twin Power belt (teeth on both sides) to reverse
rotation. Fast and Accurate!
Drive Design
Pulley Flanging Requirements
– Standard Belts Must Be Restrained On Both Sides
– Every Pulley Does Not Require Flanging
OK
15
OK
OK
Drive Design
Pulley Flanging Requirements
– Long Belt Spans May Need Additional Constraint
oBelt Spans > 8X The Pulley Diameter May Exhibit Greater Than
Normal Tracking Forces
D
8xD
o Idler Pulleys Can Be Flanged And Used To Constrain Belts As
Needed
16
Drive Design
Pulley Flanging Requirements
– Shaft Misalignment Results In Belt Tracking Force
oShaft Non-Parallelism
oShaft Deflection
– Synchronous Belts Always Track “Down Hill”
Belt
Tracking
17
Belt
Tracking
Drive Design
Drive Alignment Requirements
Ideal Alignment
– 1/4 Maximum Allowable (Angular +
Parallel)
Angular Misalignment
– Shaft Parallelism Influences Belt
Tracking
Parallel Misalignment
– Shaft Parallelism Influences Belt
Tensile Loading
18
Application: Selecting The Correct Drive
Special Characteristics
– Belt Tooth Jumping Resistance
oTooth Jumping Generally Begins At The Entry Point Into The
Driven Pulley
– Belt Pre-Tension Is Needed To Prevent Tooth Jumping
– Large Sprocket Diameters Reduce Tooth Jumping
oDrives With Short Centers Have Greater Tooth Jumping
Resistance Than Drives With Long Centers
– Short Belts Elongate Less Under Equivalent Loads
19
Application: Selecting The Correct Drive
Special Characteristics Cont.
– Belt Tooth Jumping Resistance Cont.
oMaximize Tooth Jump Resistance By:
–
–
–
–
20
Designing With A Larger Belt Pitch Drive System
Designing With Large Sprocket Diameters
Increasing Belt Installation Tension
Maintaining Rigid / Non Collapsing Center Distance
5mm PowerGrip® GT®2 – Belt Sizes Available
NOTES
PowerGrip GT2 part numbers are comprised of pitch,
pitch length and width
 For example, 5MR-400-09 signifies 5mm pitch, 400mm
pitch length and 9mm width
 Belt pitch is the distance in millimeters between two
adjacent tooth centers as measured on the pitch line of the
belt. Belt pitch length is the total length (circumference) in
millimeters as measured along the pitch line. The
theoretical pitch line of a PowerGrip GT2 belt lies within the
tensile member.
 5mm pitch, 9mm wide Long-Length Belting is designated
as LL5MR-09. Belting is available in lengths up to 300 ft.
Pitch
Pitch
Pitch
Part
No.
No. of
Teeth
Length
(In.)
Part
No.
No. of
Teeth
Length
(In.)
Part
No.
No. of
Teeth
Length
(In.)
5MR-300-09
60
11.81
5MR-575-09
115
22.64
5MR-900-09
180
35.43
5MR-355-09
71
13.98
5MR-580-09
116
22.83
5MR-1000-09
200
39.37
5MR-375-09
75
14.76
5MR-600-09
120
23.62
5MR-1150-09
230
45.28
5MR-400-09
80
15.75
5MR-625-09
125
24.61
5MR-1300-09
260
51.18
5MR-405-09
81
15.95
5MR-650-09
130
25.59
5MR-1450-09
290
57.09
5MR-425-09
85
16.73
5MR-700-09
140
27.56
5MR-1600-09
320
62.99
5MR-450-09
90
17.72
5MR-750-09
150
29.53
5MR-1720-09
344
67.72
5MR-500-09
100
19.69
5MR-800-09
160
31.5
5MR-1755-09
351
69.09
5MR-535-09
107
21.06
5MR-815-09
163
32.09
5MR-2100-09
420
82.67
5MR-565-09
113
22.24
5MR-850-09
170
33.46
5mm PowerGrip® HTD® – Sprockets Available
5mm pitch aluminum
sprockets available for
9mm and 15mm wide
belts. (For 15mm width,
please change end part
number from 09AL to
15AL)
 A complete drive system
includes the sprocket
hardware, available from
Gates as well.
No.
No. of
Grooves
Pitch Dia.
(In.)
P12-5M-09AL
P13-5M-09AL
P14-5M-09AL
P15-5M-09AL
P16-5M-09AL
P17-5M-09AL
P18-5M-09AL
P19-5M-09AL
P20-5M-09AL
P22-5M-09AL
P24-5M-09AL
P25-5M-09AL
P26-5M-09AL
P28-5M-09AL
P30-5M-09AL
P32-5M-09AL
P34-5M-09AL
P36-5M-09AL
P38-5M-09AL
P40-5M-09AL
P44-5M-09AL
P48-5M-09AL
P50-5M-09AL
P56-5M-09AL
P60-5M-09AL
P62-5M-09AL
P70-5M-09AL
P72-5M-09AL
12
13
14
15
16
17
18
19
20
22
24
25
26
28
30
32
34
36
38
40
44
48
50
56
60
62
70
72
.752
.815
.877
.940
1.003
1.065
1.128
1.191
1.253
1.379
1.504
1.566
1.629
1.754
1.880
2.005
2.130
2.256
2.381
2.506
2.757
3.008
3.133
3.509
3.760
3.885
4.386
4.511
Buying Additional Parts
 Gates sells all products only through our
Distributor network. The Gates.com website
has this information.
 Your best sources that will take credit card
orders and expedite delivery are:
B & B Manufacturing, La Porte, IN
bbman.com or 877-787-4022
York Industries Garden City, NY
York-ind.com 800-354-8466
Stock Drive Products- New Hyde Park, NY
Sdp-si.com 516-328-3300
PowerGrip GT2 – Design Manual
 Download (PDF)
your copy from
www.gates.com
 See URL below, or click through:
 www.gates.com
 Power Transmission
 Catalogs
 Drive Design Manuals
http://www.gates.com/catalogs/index.cfm?requesting=ptcatalog&location_id=524#ddm
Gates Industrial Power Transmission Catalog
 The June 2007 Gates
Power Transmission catalog
is available on www.gates.com
 Includes all PowerGrip GT2
components in your kit, as well as
all available sizes
http://www.gates.com/catalogs/index.cfm?requesting=ptcatalog&location_id=524#ddm
Contact The PowerGrip Team
 For additional questions or product-related
orders, please email the PowerGrip team at
PowerGrip@gates.com or the Gates Product
Application Help Line at 303-744-5800
 Best of luck in your FIRST competitions!
 Feel free to contact us before, during, and after
the competition for any questions,
opportunities, or inquiries you may have
Synchronous
• Poly Chain® GT® Carbon- Improved High Performance Belt
Constructed with Polyurethane Body and Carbon Fiber Tensile Cord (approx 15%
greater capacity than “old” PCGT2). More length stable. More flesible
(accomodates back-side idlers well)
•
•
Pitches Available – 8M
14M