PRONAR T669/1, Operator'S Manual, Page: 47 / 137

SECTION 3 Pronar T669/1
3.3
3.2 TRAILER CONSTRUCTION
3.2.1 CHASSIS
Trailer chassis consists of sub-assemblies indicated on figures (3.1) and (3.2). The lower
frame (1) is a structure welded from steel shapes. It may be available in two variants
depending on the unloading direction of the load box.
The main support elements are two longitudinal members connected with crossbars. In the
middle section there are sockets (11) used for mounting the tipping hydraulic cylinder. In front
of the sockets of the ram cylinder is mounted the load box support (9). At the rear part of the
lower frame there is rear beam (18) terminated with ball pins. Hydraulic and pneumatic
system sockets are mounted on the beam for connecting a second trailer. The support
structure of the upper frame allows tipping of the load box to one of the sides and to the rear,
depending on the lower frame design. The rear hitch (6) is bolted to the beam to enable
coupling the second trailer (biaxial). A pin with diameter of
∅
33 mm is suitable for connecting
with drawbar eye of
∅
40 mm. In the rear section of the chassis there are two lights support
beams (12) and 13, and rear fender (5).
Trailer suspension consists of two wheel axles (4), in a tandem arrangement suspended on
taper leaf springs (7) connected by rocker arm (8). Axles are secured to suspension springs
using absorber plates and U bolts. Axles are made from square bars terminated with a pin,
where wheel hubs are mounted on cone bearings. The wheels are single, equipped with
brake shoes activated through mechanical expander cams.
In front there is a drawbar (2) to which shear type drawbar support is mounted (3). Drawbar is
bolted to the drawbar front plate. Three types of drawbars are available: rotating drawbar (15)
with eye of
∅
50 mm (standard equipment), K80 ball drawbar (16) (optional equipment), fixed
drawbar (17) with eye of
∅
40 mm diameter (optional equipment).
Tandem chassis can be optionally equipped with a rear steering axle which improves the
tractor and trailer driving comfort on the field. In addition, steering axle facilitates change in
the driving direction, and during sharp turns does not create ruts in the ground and provides
better stability during cornering. When driving forward, the front axle follows the path of the
tractor, because the trailer wheels are directed in the opposite direction than the front wheels
of the tractor.