MARCH 20TH, 2020 across 11 different parameters accounting for five simulations each. One of the material parameters was changed from its initial value while the other parameters were kept constant. This was repeated until all New Brake Design Supports Modern E- values of the parameters were simulated. Additionally, the geometry of the sphere consisted of various editable parameters. These parameters consisted of the following: sphere radius, lining thickness, Hydraulic sphere brake delivers higher shell thickness, shell angular coverage, and the pressure angle. Like the material simulations, the geometry simulations changed one performance in a smaller package parameter at a time and held the others constant at an average value.

Based on extensive simulation using Contact Mechanics under the ADINA script at PSC, brake torque is most sensitive to sphere radius, Aaron J. Lewis, Joe Fiore, and Jason Pintea shell angular width, angular width of the pressure application area, and the coefficient of friction. The sphere concept significantly outperformed the model despite having an 84% smaller brake effective radius. Results prove that a single sphere brake is Abstract approximately equivalent to three-disc brakes in terms of braking performance given a vehicle platform equivalent to a light duty pickup In this paper, a new design of a hydraulic brake system for electric truck. Increasing the sphere radius by a factor of 1.5, from 6cm to 9cm, motorcycles is considered with better technical characteristics and increases the brake torque by more than a factor of 3. Increasing the functional abilities in comparison to existing disc brake designs called sphere radius while keeping all other design parameters the same, the Hydraulic Sphere Brake (HSB). Using validated learning through results in a greater contact area as well as a greater moment arm for the the build-measure-learn (BML) feedback loop, minimum viable contact friction. This dual effect is responsible for the large increase products (MVP) were rapidly developed that have been demonstrated in brake torque with the sphere radius. However, as the sphere radius in the lab environment. Advantages of developments in HSB increases, the weight of the sphere brake also increases. A factor of application include the following: 1) The first brake system which 1.5 increase in the sphere radius increases its weight by a factor of does not require tools to change brake pads; 2) Due to inherent design, 3.375. Finally, stopping distances were calculated for a light duty the brake itself produces more torque in a much smaller package; 3) pickup truck comparing sphere to disc brake systems. With only two The HSB is lighter than the required disc brake for the same platform; sphere brakes, the stopping distance is estimated to be about 46m. 4) It is positioned more towards the centerline of the , Technically, one sphere brake per axle outperforms four-disc brakes at increasing stability and performance; and 5) The brake is affordable in each wheel end by almost 33%. This finite element analysis (FEA) high growth industries like e-mobility. The HSB has been installed on validated that the sphere concept appeared to be sound and competitive a CycleWerks ACE motorcycle for lab testing. The new with existing brake technology. Furthermore, derivations of the HSB will be commercialized on Cleveland CycleWerks Falcon electric equations can be computed to determine sphere brake torque, sphere motorcycle (e-motorcycle). In this paper, results of experimental brake stopping distance, and comparative analysis with disc brakes in studies will be presented and discussed. The experimental results any platform. confirmed the validity of the theoretical propositions. The next step determined the feasibility in manufacturing a sphere Introduction brake system to assess the effectiveness behavior of a friction material regarding pressure, temperature, and speed for the brake system to The disc brake was invented by Frederick Lanchester back in 1902 validate FEA test results. To do this, Lewis partnered with Navitek when electricity was still in its infancy. Lanchester successfully Machining and Link Engineering. Several major achievements were integrated disc brakes on his Lanchester automobiles in Europe [1]. attained during this stage of development. First, the sphere brake can Nearly 20 years later, the Douglas Motorcycle Company used a be manufactured and tested on dynamometers. Second, the results version of the disc brake on their product lines. The Douglas was the from the dyno tests validated similar performance behavior that was first motorcycle with front and rear disc brakes to win the Senior TT captured in the FEA testing conducted at PSC. The sphere brake in 1923 rode by Tom Sheard [2]. Yet, it wasn’t until 1965 that disc prototypes generated significantly more torque than disc brakes in a brakes made their way to public markets. MV Augusta offered front much smaller package; nearly 3 times the required torque needed for disc brakes on one of their 1965 touring motorcycles. light duty truck application despite a slightly lower coefficient of introduced the first hydraulic disc brake in 1969 on the popular and friction. Third, heat needs to be mitigated and is one of the most affordable CB750 [3]. Though incremental improvements have been important Critical to Quality (CTQ) attributes for consideration as made on disc brakes, true disruption has occurred in over 50 years. development progresses.

The sphere brake was invented by Aaron Lewis back in 2010. After Given validation of the technology for light duty trucks, Lewis meeting with and receiving interest in the concept from a group of garnered support form a major commercial vehicle OEM to scale the executives within a prominent aftermarket brake company in Chicago, technology to Class 8 vehicles. Five challenges were presented to Lewis received seed funding from the Ben Franklin Technology complete the next iteration of the sphere brake. Those included: 1) Partners (BFTP) in Erie, PA to begin product validation. To derive Does not require a two-man lift; 2) Does not require wheel removal to sphere brake torque formula, Lewis partnered with The Pittsburgh service pads; 3) Has the fewest parts; 4) Is bolt-on; 5) Performs at the Supercomputing Center (PSC) at Carnegie Mellon University (CMU). same level as disc brakes. At the additional request of the Original The sphere brake model was rendered in Automatic Dynamic Equipment Manufacturer (OEM), a sphere driveline retarder was also Incremental Nonlinear Analysis (ADINA). The model consisted of the designed. Approximately 13 total units were manufactured. Of those upper right quarter of the design. ADINA simulations were performed 13, four service brakes were installed at the wheel-ends of a Mack test Page 1 of 8

| 2012 E. 33rd Street, Erie, PA 16510 | 814.898.4321x266 | www.spherebrakes.com Member SAE, NAMC, and DATC truck and one sphere driveline retarder was installed on the driveshaft. applied, hemispherical pads enclose on an outer sphere surface. This Test track demonstrations and one field test were performed on the inherent design allows multi-directional brake force application Mack test vehicle. All five challenges were met within 15 months. around the brake surface generating more torque with a smaller brake The efforts of the commercial vehicle iteration led to a Small Business effective diameter. For purposes of demonstrating the concept and Innovation Research (SBIR) contract with Marine Corps Systems how the HSB was designed and installed on an e-motorcycle Command (MCSC). To date, the sphere brake system has been application, reference Figure 1 below for the governing equations in designed on 3 military platforms with both pneumatic and hydraulic the following section. actuation. The bolt-on sphere brake shed over 50lbs. per wheel-end and it’s the first brake that doesn’t require wheel removal to change brake pads.

To accelerate product commercialization and validation, the sphere brake has been scaled down to racing and two wheeled applications within high growth industries that promote innovation. Industries like electric motorcycles and scooters enable market entry that promote disruptive technologies without sacrificing quality over cost and affordability. The global electric two wheeled industry is estimated to reach $13,864 million by 2025 [4]. North America is estimated to reach $675.7 million by 2024, with a CAGR of 28.4%. US is the larger market in the North America region, holding 85% of the market share [5]. Furthermore, new electric motorcycle manufacturers are starting up across the US. Some are brand new. Others already have well established markets with internal combustion engine (ICE) product lines. One such manufacturer is Cleveland CycleWerks based in Cleveland, OH. A manufacturer who is launching their very first e- mobility platform, The Falcon. A platform that will feature exciting, new technology that has yet to be commercialized in any market. With lower barriers to entry and the speed at which development iterations can occur, Sphere Brakes (SB) partnered with Cleveland CycleWerks to launch the world’s first HSB for e-motorcycles.

This paper proposes the first HSB for e-motorcycles starting with an overall description of the design, formulas for calculating torque, and considerations of optimizing the brake component setup to achieve Figure 1. HSB design for e-motorcycle application. desirable stopping distances. Next, the Lean Startup Model is introduced as a means of executing high risk research and development Before any modeling or testing could commence, brake torque and of disruptive technology. As validated learning is of most importance, stopping distance formulas had to be solved. Modeling, prototyping, results from testing hypotheses through voice of customer (VOC) and limited field testing based on the following formulas will be visits, leveraging CAD modeling, and limited stopping distance tests discussed in the Validated Learning section later in this paper. are presented. Finally, implications of sphere brake technology on e- motorcycles as a holistic solution to increase performance and range, Sphere Brake Torque Formula Theoretical Considerations while maintaining safety are discussed. The paper concludes with recommendations for future work. This section provides a summary of the governing equations that were used in sphere brake torque analysis derived by Dr. Anirban Jana from The Sphere Brake System PSC. To find brake torque from Automatic Dynamic Incremental Nonlinear Analysis (ADINA) software, the following formulas were The bolt-on configuration of the hydraulic sphere brake system used. presented here generally satisfies NHTSA’s definition of existing air brake systems under 49 CFR Part 571.105 as a, “system that uses The following equation gives the representation of dA, an infinitesimal hydraulic fluid as a medium for transmitting force from a service brake piece surface area, in spherical geometry. This surface element spans control to the service brake, and that may incorporate a brake power from θ → θ + dθ and from → + d . assist unit, or a brake power unit [6].” ∅= ∅sin ∅ General Design of the Sphere Brake 2 (1) 𝑑𝑑𝑑𝑑 𝑟𝑟 𝜃𝜃𝜃𝜃𝜃𝜃𝜃𝜃𝜃𝜃𝜃𝜃∅ Here is the equation which presents an infinitesimal friction vector. The two most common brake systems used in two wheeled applications are drum and disc brakes. The drum brake leverages an inner expansion design. When the brake is applied pads expand out = from the axle towards the drum surface radially. Disc brakes use a (2) 𝑑𝑑⃑𝑓𝑓 𝜇𝜇𝜇𝜇𝜇𝜇𝜇𝜇 ∗ 𝑓𝑓̂ simple c-clamp concept. When the brake is applied, pads “clamp” to We can also describe the braking pressure, friction and dN as vectors. opposing sides of the discs axially inward. The sphere technology dN is the normal vector from the surface. leverages axial compression in lieu of expansion. When the brake is

Page 2 of 8

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= + + The master cylinder is designed to take the input force from the lever (3) and convert that force into working pressure that can be distributed to 𝑃𝑃�⃑ 𝑃𝑃1𝑒𝑒1̂ 𝑃𝑃2𝑒𝑒̂2 𝑃𝑃3𝑒𝑒̂3 the hydraulic sphere brakes at the wheels. To calculate this pressure the input force from the lever is divided by pi over 4 times the diameter = + + of the master cylinder piston squared as expressed below: (4) 𝐹𝐹⃑𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓 𝐹𝐹1𝑒𝑒1̂ 𝐹𝐹2𝑒𝑒̂2 𝐹𝐹3𝑒𝑒̂3 = = ( . ) (5) 4 𝐹𝐹𝑖𝑖 𝑑𝑑𝑁𝑁��⃑ −𝑃𝑃𝑃𝑃𝑃𝑃 ∗ 𝑛𝑛� 𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃 𝜋𝜋 2 (12) ∗ 𝑃𝑃𝑃𝑃𝑃𝑃344𝑃𝑃.𝑃𝑃8 Now we can continue with describing df. If we wish to calculate df 1.216 / = we can use the following equation to do that. (19 ) 2 4 𝑁𝑁 𝑁𝑁 𝑚𝑚𝑚𝑚 𝜋𝜋 2 (13) ∗ 𝑚𝑚𝑚𝑚 𝜋𝜋 To calculate brake clamping force, pressure is converted to MPa. Yet = 2𝜋𝜋 4 𝑅𝑅 first, the area of one piston must be determined. Since the HSB is a 2 fixed brake system, pi divided by 4 multiplied by the diameter of the 𝑑𝑑𝑑𝑑 𝜇𝜇𝜇𝜇 � � � 𝑟𝑟 𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 𝑑𝑑𝑑𝑑 𝑑𝑑𝑑𝑑 𝑑𝑑∅ (6) 0 0 0 brake caliper piston squared determines the area. Since the piston is a donut, the ID must be subtracted from the OD as expressed below: Now using the equations above, we can formulate an equation for the braking torque. = ( 4 𝜋𝜋 2 2 (14) 𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶𝐶 𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃 𝐴𝐴𝑟𝑟𝑟𝑟𝑟𝑟 ∗ 𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃 𝑂𝑂𝑂𝑂 − 𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃 𝐼𝐼𝐼𝐼 = ( + ) 6481.14 = (9216 959.76 ) 4 𝐵𝐵𝐵𝐵𝐵𝐵𝐵𝐵𝐵𝐵 ⃑ �����⃑ 2 𝜋𝜋 𝑇𝑇 � 𝑟𝑟⃑ 𝑥𝑥 𝑑𝑑𝑓𝑓 𝑑𝑑𝑁𝑁 (7) (15) 𝑠𝑠𝑠𝑠ℎ𝑒𝑒𝑒𝑒𝑒𝑒 𝑚𝑚𝑚𝑚 ∗ 𝑚𝑚𝑚𝑚 − 𝑚𝑚𝑚𝑚

After some manipulation, the brake torque equation can be written as Given the brake clamping force pressure from formula 5 and the brake the following. caliper piston area from formula 7, the front brake tire contact force can be determined. To calculate this force, the effective brake radius ( ) is divided by the rolling radius of the tire ( ) which is then 𝜃𝜃𝑓𝑓 = sin( ) multiplied by the number of brake pads, coefficient of friction ( ), area 2 𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟 𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟 𝐵𝐵𝐵𝐵𝐵𝐵𝐵𝐵𝐵𝐵 of the piston caliper ( ), and the input pressure ( ) 𝑑𝑑 𝑇𝑇 −𝑃𝑃𝑃𝑃𝑃𝑃𝑟𝑟 � 𝜃𝜃 𝑑𝑑𝑑𝑑 (8) 𝜇𝜇 𝜃𝜃0 as expressed below: 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃 𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃 If we assume is zero, we get the following equation. = 1 * 0 𝑟𝑟𝑟𝑟𝑟𝑟𝑟𝑟 𝜃𝜃 𝐶𝐶 𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃 (16) = [1 ( ) ] 𝐹𝐹 �𝑟𝑟𝑟𝑟𝑟𝑟. 𝑟𝑟� ∗ ∗ 𝜇𝜇 ∗ 𝐴𝐴𝐴𝐴𝐴𝐴𝑎𝑎 𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃 2 (9) 734.9 = 1 .44 6481.14 * 1.21 𝐵𝐵 𝑓𝑓 𝜏𝜏 𝑃𝑃𝑃𝑃𝑃𝑃𝑟𝑟 − 𝐶𝐶𝐶𝐶𝐶𝐶 𝜃𝜃 60 7𝑚𝑚𝑚𝑚 2 (17) 𝑁𝑁 �285𝑚𝑚𝑚𝑚 � ∗ ∗ ∗ 𝑚𝑚𝑚𝑚 𝑀𝑀𝑀𝑀𝑀𝑀 Sphere Brake Formulae to Form, Fit, Function Given the small coverage arc of the pads, the spherical gain is about This section provides a summary of the governing equations that were 5%. That increases the force to 771.6N. To calculate total brake force used to determine the proper form, fit, function of the hydraulic sphere on the Falcon e-motorcycle, the front brake force and rear brake force brake for the Falcon e-motorcycle manufactured by Cleveland are combined. A general rule of thumb is that 60% of the total brake CycleWerks. The basis of design is to meet and exceed stopping is applied to the front of the motorcycle and 40% is applied to the rear distance requirements specified in FMVSS 122 for initial velocities of brake. Therefore, the brake force applied to the Falcon is 771.6N 30mph (44ft/s), 60mph (88ft/s), and 90mph (132ft/s). (60%) plus 517N (40%) which totals 1288.66N of total brake force.

The first formula calculates the lever ratio of a rider applying force to The amount of deceleration is dependent on total mass which combines determine the input force to the master cylinder whereby the length of the mass of the Falcon at 133kg plus the weight of a 100kg rider totaling 233kg. To calculate deceleration the force is divided by the the lever ( ) of 201.9mm is divided by the working length of the lever ( ) or 40.6mm given a hand force ( ) of 70N equates to 348.1N as mass as expressed below: 2 expressed𝐿𝐿 below: 𝐿𝐿1 𝐹𝐹𝑃𝑃 = / = / * (18) 𝑎𝑎 𝐹𝐹 𝑚𝑚 (10) 𝐹𝐹𝑖𝑖 𝐿𝐿2 𝐿𝐿1 𝐹𝐹𝑃𝑃 1288.66 = = 5.53 / 200 233 344.8 = 70 𝑁𝑁 2 40.6 𝑎𝑎 𝑚𝑚 𝑠𝑠 (19) 𝑚𝑚𝑚𝑚 (11) 𝑘𝑘𝑘𝑘 𝑁𝑁 ∗ 𝑁𝑁 𝑚𝑚𝑚𝑚 Page 3 of 8

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Since stopping distance will be measured in ft, 5.61m/s2 is converted to build that customers will pay for through fast iteration and customer first to 0.572g, then to 18.418 ft/s/s. To determine if the current insight. The Lean Startup Model, developed by Eric Ries, offers configuration meets FMVSS 122 stopping distance requirements, several principles through a build-measure-learn feedback loop that three (3) initial velocities were selected to compute stopping distance ensures whether a product delivers value to a potential customer [7]. estimates from 30mph (44ft/s), 60mph (88ft/s), and 90mph (132ft/s). There are five principles to the lean startup model. Two principles have To determine stopping distance (SD), initial velocity ( ) squared is been applied to sphere brake development which are defined below. divided by 2X the deceleration rate as expressed below: 𝑖𝑖 𝑉𝑉 Build-Measure-Learn (BML) = 2( 2 ) The first product cannot be perfect. Known as the BML feedback loop, 𝑉𝑉𝑖𝑖 𝑆𝑆𝑆𝑆 (20) this principle provides a foundation to make cost efficient decisions 𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷 when faced with complex research challenges developing high risk For 44ft/s: technology. Drew Houston, CEO and Founder of Dropbox, leveraged 1936 Ries’ feedback loop to build a video highlighting a working prototype 53.3 = 36.25 demonstrating a snapshot of the Dropbox application in about 3 (21) minutes to get the point across on how it works and what the interface 𝑓𝑓𝑓𝑓 looks like; not the product itself! It was presented to investors at the Y For 88ft/s: Combinator which in turn provided him with valuable product 7744 feedback and an offered investment. The video MVP was so 213.5 = 36.25 successful that the Dropbox team uploaded it to Digg.com and within (22) 24 hours had secured a waitlist of 75,000 users. Dropbox experienced 𝑓𝑓𝑓𝑓 rapid growth from 100,000 users at public launch to 4 million in 15 For 132ft/s: months with sustained growth of 15-20% since the launch. As Houston 17424 states, “There’s lots of pressure to do things the traditional way. But 480 = 36.25 it’s important to put something in user’s hands early. Make something (23) that’s simple and just works to make them happy [8].” 𝑓𝑓𝑓𝑓 Taking into consideration the current brake configuration for the Validated Learning Falcon e-motorcycle with an HSB installed on the front and rear wheels meets required stopping distance requirements of 54ft, 216ft, “Progress in manufacturing is measured by the production of high- and 484ft respectively. Lever stroke length to achieve the force quality goods. The unit of progress for Lean Startups is validated required to meet SD requirements with the current HSB configured learning; a rigorous method for demonstrating progress when one is Falcon can be calculated. Total lever travel is a function of the lever embedded in the soil of extreme uncertainty,” emphasizes Ries [9]. To ratio multiplied by the master cylinder stroke. Master cylinder stroke validate the value hypothesis, an MVP must be developed quickly, to is a function of piston area, retract distance, and master cylinder area measure effectively, to persevere or pivot efficiently. The following as expressed below: subsections each represent one turn of the feedback loop in the development of the sphere brake technology by providing a framework ( which presents value hypotheses, applications, and results that = )* 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃 . promote validated learning. 𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀 𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃 (24) 𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀 𝐶𝐶𝐶𝐶𝐶𝐶 𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷

. CAD Modeling Iteration 13.72 ( 0.6 = . )* 6481 14𝑚𝑚𝑚𝑚 (25) The design had to have a new aesthetic, one not seen in any market 𝑚𝑚𝑚𝑚 283 38𝑚𝑚𝑚𝑚 𝑚𝑚𝑚𝑚 To determine lever travel: before yet functional and clean representing the e-mobility industry. It had to look different than existing sphere brakes, scaled down from = * Class 8 commercial vehicle applications to very light weight platform (26) integration in a very tight packaging space. Current sphere brakes 𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿 𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝑟𝑟 𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀 𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇 𝑅𝑅𝑅𝑅𝑅𝑅𝑅𝑅𝑅𝑅 𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 apply force perpendicular to the axis of rotation. The new HSB applies 67.59 = 4.92*13.72 force parallel to the axis of rotation as described in the previous (27) formula section. This change was necessary to accommodate 𝑚𝑚𝑚𝑚 𝑚𝑚𝑚𝑚 packaging the most effective brake surface area between the fork and Therefore, the rider must stroke the lever 67.59mm (2.6in) with the wheel hub. This design also shifted weight closer to the centerline 116.7N of force to achieve the stopping distance requirement given the of the motorcycle increasing stability and front-end performance. Falcon with two HSB’s installed on the front and rear wheels. In the first turn through the BML loop, CAD modeling was used to validate the first four value hypotheses. First, the HSB can be modeled The Lean Startup Model as a bolt-on kit to an existing motorcycle platform without axle, hub, or fork modification. Second, the HSB can be designed to affordable Due to the extreme uncertainty and limited funding startups face while manufacturing. Third, the HSB can be designed to allow no-tool brake developing disruptive technology, a new approach to research and pad removal without sacrificing safety, performance, or quality to design must be implemented and executed through to design. Fourth, the HSB can be designed as the lightest on the market commercialization. The goal of a startup is to figure out the right thing with the fewest amount of parts. The first iteration HSB that was Page 4 of 8

| 2012 E. 33rd Street, Erie, PA 16510 | 814.898.4321x266 | www.spherebrakes.com Member SAE, NAMC, and DATC installed on the Cleveland CycleWerks ACE motorcycle is shown in brake lever setup. All modifications to parts were made, changes to Figure 2 below. The first iteration validated a couple of the drawings were recorded and updated, and a new 19MM radial master hypotheses. cylinder lever was installed on the ACE in preparation for limited stopping distance tests. Figures 4 and 5 below capture the first iteration HSB installed and functioning on the ACE motorcycle.

Figure 2. First iteration HSB modeled on CLEVELAND CYCLEWERKS ACE motorcycle.

Iteration 1 has fewer than 8 parts and bolts on to an existing motorcycle platform without axle, hub, or fork modifications. HSB Iteration 2 met all four hypotheses and will be installed on Cleveland CycleWerks Falcon e-motorcycle shown in Figure 3 below.

Figure 4. HSB iteration 1 installed on ACE.

Figure 3. Second iteration HSB on the Falcon.

The 2nd iteration HSB bolts-on to the Falcon as a kit. It has only 8 parts and weighs less than 2lbs. No tools or lifts are required to change brake pads. Furthermore, the HSB is affordable for e-motorcycle platforms and manufacturers. No special materials or expensive manufacturing processes are used to produce each component.

Bolt-on Mock-Up Iteration

Building upon CAD modeling, the second turn through the BML loop Figure 5. 19mm radial master cylinder setup. focused on three additional value hypotheses that occurred in a shorter duration than the first iteration. First, that the HSB can be Limited 30mph Stopping Distance Iteration manufactured using existing industrial machinery, tools, and processes. Second, that a physical MVP confirms the form, fit, The final turn through the BML loop focused on five additional value function from CAD modeling on an actual motorcycle. Third, that the hypotheses that occurred in a shorter duration than the second iteration. MVP can function using off the shelf (OTS) certified master cylinders First, that the HSB can stop within specified FMVSS 122 stopping and brake lines. distance requirements as a single unit from 30mph. Second, that the HSB can stop within 54ft in combination with rear braking on the The first iteration HSB was installed on the Cleveland CycleWerks motorcycle from 30mph. Third, that the HSB doesn’t leak hydraulic ACE platform. There were some minor fit up issues relating to front fluid. Fourth, that the HSB doesn’t cause vibration. Fifth, that the end spacing along the axle plane, some slight interference with the HSB doesn’t overheat. housing to fork profile, and adjustments to the master cylinder front Page 5 of 8

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With the HSB installed on the front wheel with a standard disc brake mounted on the rear wheel of the Cleveland CycleWerks ACE, multiple stopping distance iterations were performed on a local asphalt road with a general coefficient of friction of .68. All tests were performed between 320F and 390F. Tables 1 and 2 capture 12 stopping distances from 30 mph which all meet and exceed the FMVSS 122 requirement of 121ft for single brake application and 54ft of combo (front/rear) brake application. (ft)

.

Stop Number Stop Distance (ft) Pass Rqmt Under 1 112 YES 9

2 94 YES 27

3 91 YES 30

4 88 YES 33

5 92 YES 29

6 83 YES 38

Table 1. 30mph stopping distance results for HSB on ACE.

(ft)

.

Summary Stop Number (ft) Distance Pass Under Rqmt 1 37 YES 17 The HSB is fundamentally different than disc or drum brake technology. A description of how the HSB functions was introduced. 2 32 YES 22 Formulas were presented to determine form, fit, and function of the HSB on an e-motorcycle platform. Through the BML feedback loop, three rapid iterations of design, development, and testing were 3 37 YES 17 accomplished. Given a Cleveland CycleWerks ACE motorcycle, stopping distance performance was calculated and validated through 4 34 YES 20 limited field testing.

5 37 YES 17 Multiple value hypotheses were validated. Most notably include that the HSB is the first brake that doesn’t require tools to remove brake 6 37 YES 17 pads. The mass of the HSB is positioned closer to the centerline of the e-motorcycle platform and is lighter than existing disc brake systems Table 2. 30mph stopping distance using both the HSB and rear disc. for similar platforms. Inherent design enables increased brake torque in a smaller package. The sphere effect increases brake torque at the Figure 6 shows stopping distance conditions in Erie, PA. wheel compared to a disc brake in similar configuration. The HSB can be manufactured with modern tooling and production processes without exotic materials.

The value the HSB delivers to both manufacturers and riders is immediate. It is a 21st century brake for a 21st century e-mobility solution without sacrificing performance, quality, or safety.

Future Work

Since the HSB performed to our expectations throughout all test scenarios, this paper is a good vantage point for further research into Page 6 of 8

| 2012 E. 33rd Street, Erie, PA 16510 | 814.898.4321x266 | www.spherebrakes.com Member SAE, NAMC, and DATC optimizing this technology. Future iterations of design must consider BFTP Ben Franklin Technology right sizing OTS certified master cylinders and brake lines that offer Partners the most brake force and fluid displacement ratio for both front and rear HSB units. Heat dissipation is another CTQ that may be optimized BML Build-Measure-Learn loop through selection of materials, mass, and cooling features. The technology has demonstrated an ability to scale efficiently to different CAD Computer Aided Design platforms within the e-motorcycle industry. FEA Finite Element Analysis References FMVSS Federal Motor Vehicle 1. http://www.lanchesterinteractive.org/d-disc-brakes/. Safety Standards 2. https://cybermotorcycle.com/marques/douglas/douglas-1923- ra.htm. HSB Hydraulic Sphere Brake 3. https://www.topspeed.com/motorcycles/motorcycle- reviews/honda/1969-1978-honda-cb750-ar40344.html. ICE Internal Combustion Engine 4. https://www.psmarketresearch.com/market- analysis/electric-scooter-and-motorcycle-market NHTSA National Highway 5. https://www.globenewswire.com/news- Transportation Safety release/2019/03/11/1750960/0/en/North-America- Administration Electric-Scooters-and-Motorcycles-Market-to-Reach-675- 7-million-by-2024-P-S-Intelligence.html OEM Original Equipment 6. National Highway Transportation Safety Administration, Manufacturer “Federal Motor Vehicle Safety Standards; Hydraulic Brake Systems,” 49 CFR Part 571.105, NHTSA-2009-0083. OTS Off-The-Shelf 7. Ries, Eric. The Lean Startup. New York: Crown Business, 2011. 20-61, ISBN 978-0-307-88789-4. PSC Pittsburgh Supercomputing 8. Houston, D., “Dropbox,” Center www.slideshare.net/gueste94e4c/dropbox-startup-lessons- learned-3836587, Case Study Presentation at the Startup SB Sphere Brake Lessons Learned Conference 2010, Apr, 2010. 9. The Lean Startup Methodology, “Validated Learning,” http://leanstartup.com/principles, accessed Dec. 2016. SBIR Small Business Innovation Research

Contact Information SD Stopping Distance

Aaron J. Lewis, P.M.P. VOC Voice of Customer [email protected]

Acknowledgments

The authors would like to thank the staff at Cleveland CycleWerks, Applied Vehicle Sciences, Inc., Reddog Industries, the Pittsburgh Supercomputing Center, Ben Franklin Technology Partners, and mentors from Endless Frontier Labs for providing the necessary infrastructure and support for the execution of the above work. They would also like to thank Jianna Salinas (Team Scrappers), Karen Stoffer (Ray Skillman Racing), and Ryan Rzepecki (JUMP/UBER) for providing customer insight and feedback on the perceived advantages sphere brake technology may bring to the two-cycle industry.

Definitions/Abbreviations

ADINA Automatic Dynamic Incremental Nonlinear Analysis

CAGR Compound Annual Growth Rate

Page 7 of 8

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CCW Cleveland CycleWerks

CFR Code of Federal Regulations

CMU Carnegie Mellon University

CTQ Critical to Quality

MCSC Marine Corps Systems Command

MVP Minimum Viable Product

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