Brake system
A brake system for a bicycle is disclosed. The brake system comprises an actuation mechanism shown as a master cylinder assembly and a brake or brake mechanism for the wheels of the bicycle. The mechanism/assembly comprises (among other parts, components and assemblies) a body or housing, a piston assembly, an actuating lever on a pivot pin, a bladder, a retainer and a primary seal. The bladder is fixed at a first end to the piston and fixed at a second end to the retainer. A reservoir is defined by the piston, the body, and the bladder. Advancement of the piston along the stroke causes the piston to seal against a primary seal and separate the reservoir from a pressure chamber in the body. A retainer may be provided to seal the bladder to the body, act as a piston guide bushing, act as a pivot bushing, and act as a stroke limiter. Upon advancement the piston will contact the primary seal and separate the reservoir from the pressure chamber as the bladder rolls out thus pressurizing the fluid. Stroke is limited at one end by a feature on the retainer which contacts the cam surface on the lever preventing further rotation/movement and at the other end by a stop pin.
1. A brake system of a type with a master cylinder using a fluid comprising:
(a) a body;
(b) a piston;
(c) a bladder connected to the piston to define a reservoir having a volume to contain fluid;
(d) a lever to actuate the piston;
wherein the body comprises a pressure chamber having a volume so that (a) advancement of the piston reduces the volume of the pressure chamber and (b) retraction of the piston expands the volume of the pressure chamber;
wherein the body comprises a seal for the piston and the pressure chamber;
wherein the lever is configured so that during operation of the lever a cam surface operated by the lever will engage a flat cam surface to actuate the piston.
2. The system of claim 1 further comprising a retainer within the body.
3. The system of claim 2 wherein the bladder is retained at the retainer.
4. The system of claim 3 wherein the bladder is retained at a first end of the piston.
5. The system of claim 1 wherein during advancement of the piston in the body the piston is engaged with the seal.
6. The system of claim 5 wherein a piston cap is mounted on the piston.
7. The system of claim 6 further comprising the flat cam surface on the piston cap.
8. The system of claim 1 further comprising a lever assembly comprising the lever and a cam; wherein the cam provides the cam surface; and wherein the lever pivots on a pin and the pin provides a knurled surface for connection to the lever by an interference fit.
9. A brake system of a type using fluid comprising:
(a) a body defining a chamber having a volume;
(b) a piston movable within the chamber of the body;
(c) a bladder connected to the piston to define a reservoir having a volume to contain fluid;
(d) a lever to actuate the piston;
(e) a retainer for the bladder;
wherein the bladder is retained by the retainer at a first end and retained by the piston at a second end;
wherein actuation of the lever advances the piston into the chamber and reduces the volume of fluid in the chamber;
wherein the retainer is configured to limit advancement of the piston.
10. The system of claim 9 wherein the lever is pivoted on a pin; and wherein the pin provides a knurled surface for connection to the lever by an interference fit.
11. The system of claim 9 wherein the lever operates by cam action on the piston.
12. The system of claim 11 further comprising a piston cap on the piston to provide a cam surface for engaging a cam surface on an end of the lever.
13. The system of claim 9 wherein the bladder is retained by the retainer at a first end and retained by the piston at a second end; wherein the retainer seals the bladder to the body.
14. The system of claim 9 wherein the retainer comprises a guide for the piston.
15. A brake system comprising:
(a) a body defining a chamber;
(b) a piston movable within the body;
(c) a lever to actuate the piston;
(d) a pin for the lever to secure the lever in the body and facilitate rotation of the lever when actuated to advance the piston into the chamber;
(e) a bladder connected to the piston to define a reservoir having a volume to contain fluid;
wherein the pin comprises at least one end section and a generally intermediate section to secure to the lever;
wherein the intermediate section of the pin has a larger effective diameter than each end section.
16. The system of claim 15 wherein the intermediate section of the pin is connected to the lever by interference fit.
17. The system of claim 16 further comprising a cam actuated by the lever.
18. The system of claim 17 wherein the cam rotates about the intermediate section of the pin.
19. The system of claim 18 wherein the pin is coupled to the body on a mounting.
20. The system of claim 18 wherein the mounting comprises a clevis.
21. The system of claim 18 further comprising a piston cap on the piston to provide a cam surface for engaging a cam surface on an end of the lever.
22. The system of claim 15 wherein the bladder is retained by a retainer at one end and by the piston at another end.
23. The system of claim 22 wherein actuation of the lever advances the piston into the chamber and reduces the volume of fluid in the chamber.
24. The system of claim 15 wherein the intermediate section of the pin is knurled.