I am currently working on a tank-like robot and need some advice regarding the tracks and sprockets. Here are the details of my setup and the components I am considering:
Tracks:
Model: Lynxmotion Track System (TRK-02)
Material: Rugged polypropylene links with a Shore A hardness of 45
Dimensions: Each track link is 3 inches wide, and the pitch is 1.07 inches
Components:
21x 3’’ wide track links
21x axles
Nylon snap rivet fasteners
Assembly: Modular and easy to interconnect, but requires some assembly
Motors:
Description: High-power DC geared motors
Nominal Voltage: 18VDC
Rated Torque: 92 kgf.cm (9 Nm)
Rated Speed: 260 RPM
Rated Current: 18.7A
Rated Power Output: 250W
Gear Ratio: 1:60 (internal to the motor)
Shaft Diameter: 8mm
Quantity: 4 motors (2 per track)
Questions:
Durability: Can the Lynxmotion TRK-02 tracks withstand the torque of 2 motors each providing 9 Nm without snapping or excessive wear? Has anyone tested these tracks under similar conditions?
Sprocket Compatibility: I need sprockets that fit an 8mm motor shaft and are compatible with the Lynxmotion tracks. Does anyone have recommendations for sprockets that they have successfully used with this setup?
General Advice: Any additional tips or considerations for using these tracks and motors in a competition setting would be greatly appreciated.
Durability: Can the Lynxmotion TRK-02 tracks withstand the torque of 2 motors each providing 9 Nm without snapping or excessive wear? Has anyone tested these tracks under similar conditions?
The main uses we have for these tracks are for the following products:
The specs for the 3" tracks are:
Strength: 500 pounds per foot
Weight: 0.6 pounds per square foot
Center to center: 1.07" nominal
Plastic: Grey polypropylene
We have seen these tracks used on larger robots, but because of the small sprocket tooth size, it’s not advised.
Sprocket Compatibility: I need sprockets that fit an 8mm motor shaft and are compatible with the Lynxmotion tracks. Does anyone have recommendations for sprockets that they have successfully used with this setup?
Sounds like you need the Lynxmotion MTS with an external hub:
General Advice: Any additional tips or considerations for using these tracks and motors in a competition setting would be greatly appreciated.
Given that the sprocket is single row, you might consider using two. If it’s a long track, you might need a tensioner. If you plan to drive the sprocket directly from the motor, be sure you’re aware of the motor’s radial force so it’s not forced off-center.
Based on the specs you provided, the Lynxmotion TRK-02 tracks have a strength of 500 pounds per foot, which translates to approximately 2224 N per foot. Given that each motor produces a force of 180 N with a 10 cm diameter sprocket, the tracks should be able to handle the combined force of 360 N per track (from two motors) without snapping or excessive wear.
I understand the concern about the small sprocket tooth size. I will ensure proper alignment and tensioning to mitigate this issue.
Sprocket Compatibility:
I will use the Lynxmotion MTS 15T Sprocket with the 8mm Shaft Universal Aluminum Mounting Hub as recommended. This combination should provide a secure fit and reliable performance.
General Advice:
I will consider using two sprockets per track to ensure even force distribution and better track tension.
I will also look into adding a tensioner to maintain proper track tension.
I will ensure that the motor’s radial force is managed to prevent it from being forced off-center by securing the motor and sprocket assembly properly.
Additionally, I have a follow-up question:
If I need to extend the motor shaft and use a shaft coupler, will this affect the torque or force applied to the tracks? Are there any specific considerations I should keep in mind when using a shaft coupler?
Using a shaft coupler or extending the motor’s shaft tends not to affect the torque of a motor because there’s no offset load (it’s all axial). Many products extend the motor’s shaft but incorporate a way to mechanically support the end of it (with a bearing) to ensure it stays straight and the radial force exerted by the tracks, and still rotates freely.
One of the biggest considerations when designing a tracked vehicle is the choice of drive motors - skid steering is not efficient at all.
