Motorcycle frame

A motorcycle having an improved, lightweight, high strength frame formed from castings and stampings that are welded to each other.

BACKGROUND OF THE INVENTION 
This invention relates to a motorcycle frame and more particularly to an 
improved, lightweight frame for a wheeled vehicle such as a motorcycle. 
There are a wide variety of motorcycle or motorcycle type vehicles that are 
designed to be ridden by a single rider and which have at least one 
dirigible front wheel that is supported for steering movement directly by 
the frame. With this type of vehicle, it is desirable to provide a very 
light weight for the frame because the lighter weight permits better 
handling, better fuel economy and improved performance. However, the frame 
must, in addition to carrying the engine and rider, absorb all of the 
suspension loads of the vehicle. Therefore, frames of the type heretofore 
proposed have been quite heavy. 
It is, therefore, a principal object of this invention to provide an 
improved lightweight and simplified frame for a motorcycle type vehicle. 
It is another object of this invention to provide an improved lightweight 
and highly strong frame. 
SUMMARY OF THE INVENTION 
This invention is adapted to be embodied in a frame for a motorcycle type 
vehicle having a head pipe that is adapted to dirigibly support at least 
one front wheel. A main frame member is affixed at its forward end to the 
head pipe and has a pair of portions that extend rearwardly from the head 
portion and diverge therefrom to provide a generally triangular shape. An 
engine supporting member is affixed to the rear end of each portion of the 
main frame portion. A seat carrying member is affixed to the rear end of 
the main frame member and extends rearwardly therefrom. The connection 
between the seat member and the main frame member is forwardly of the 
engine supporting member. A reinforcing bracket extends between the engine 
supporting member and the seat frame member between the ends of the seat 
frame member for providing additional support for it.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now in detail to the drawings and initially primarily to FIG. 1, 
a motorcycle embodying the invention is identified generally by the 
reference numeral 11. The motorcycle 11 includes a frame assembly, 
indicated generally by the reference numeral 12, and includes a head pipe 
13 that dirigibly supports a front wheel 14 by means of a front fork 
assembly 15. The front fork assembly 15 is connected to a handlebar 16 for 
steering of the front wheel 14 in a known manner. 
An engine transmission assembly, indicated generally by the reference 
numeral 16, is supported within the frame assembly 12 in a manner to be 
described and drives a rear wheel 17 that is suspended from the frame 
assembly 12 by means of a trailing arm 18. 
A rider's seat 19 is supported upon the frame assembly 12 and is positioned 
rearwardly of a main cowling 21 that encloses, among other things, an air 
cleaner 22 for the induction system of the engine 16 and a fuel tank 23. 
Referring now primarily to FIGS. 2 and 3, the frame assembly 12 and its 
construction will be described. The frame assembly 12 includes, as has 
been noted, the head pipe 13 which may be formed from a lightweight 
material such as aluminum. A pair of main frame members 24 are affixed at 
their forward ends to the head pipe 13 and extend rearwardly and in an 
divergent fashion from the head pipe 13 to form a generally triangular 
configuration as shown in top plan (FIG. 3). The main frame members 24 may 
be formed from either a casting or stampings and have a generally 
box-shaped configuration. At their rear ends, each of the main frame 
members 24 is connected, as by welding, to an engine and trailing arm 
support member 25 which is also formed from a lightweight material such as 
aluminum. The engine and trailing arm support members 25 may be either 
formed as weldments or may be made as castings. A pair of down tubes 26 
(FIG. 1) are affixed to the main frame members 24, as by bolting, and to 
the engine and trailing arm supporting members 25, as by bolting to a 
flange 27 of the latter. 
In order to facilitate the attachment of the engine and trailing arm 
supporting members to the main frame members 24, the engine supporting 
members 25 are formed with projections 28 that extend into complementary 
shaped openings 29 formed at the rear end of the main frame members 24 and 
a weld joint around their periphery completes this connection. 
The engine supporting members 25 are provided with a first series of 
openings 32 that receive an engine mount 33 (FIG. 1) so as to support the 
rear end of the engine transmission assembly 26. The forward end of the 
engine is supported on brackets 34 that are affixed, as by welding, to the 
down tubes 16 (FIG. 1). 
A pair of seat supporting rails 35 are affixed at their forward ends to 
respective of the main frame members 24, as by welding. It should be noted 
that this attachment is formed forwardly of the attachment of the engine 
and trailing arm supporting member 25 to the main frame members 24. 
Intermediate the ends of the seat supporting rails 35, there is provided a 
reinforcing bracket 36, which may be formed from a lightweight material 
such as aluminum and which is affixed, as by welding, to the engine 
supporting member 25. The seat supporting rails 35 may be tubular or may 
be formed as square tubing sections and are connected to each other at 
their rearward ends by means of a plate 36. The rear end of the seat 
supporting members 35 is supported from the engine supporting member 25 by 
means of a pair of seat pillar rails 37 which, in turn, are formed from a 
lightweight material such as aluminum and may be either cylindrical or 
square tubular sections. The supporting members 25 are formed with 
upwardly extending projections 38 to which the seat pillar rails 37 are 
affixed, as by welds or socket joints 39. 
The forward end of the trailing arm 17 is journaled in the engine and 
trailing arm supporting member 25 by means including a pair of aligned 
apertures 41 formed in the members 25 to receive suitable pivot pins. The 
supporting members 25 are further joined to each other by a bridging 
member 42 so as to further reinforce the frame assembly. The bridging 
member 42 may also be formed from a lightweight material such as aluminum. 
It should be readily apparent from the foregoing description that the frame 
assembly is extremely light in weight and yet is very robust and strong. 
Although an embodiment of the invention has been illustrated and 
described, various changes and modifications may be made without departing 
from the spirit and scope of the invention, as defined by the appended 
claims.