Hand grass shears

The swivel joint of the shears comprises a dish-like rotary head 14 which is moulded from plastic and which is inserted with an inner bush 46 into a swivel joint bush 44 of an extension provided with the fixed upper grip 10. The axial fixing is via a detent means 54, 56. On the rotary head 40 the lower blade 50 is fixedly disposed and the upper blade 68 is pivotal on a bearing bush 58 of the rotary head. A pull rod 78 led through the bush 46 is anchored with a bent end to the movable upper blade laterally of the pivot axis thereof. The other end is anchored in an adjustment bush 82 which is adjustably fixed in an adjustment pin 84. The locking is by a plastic slide 24 which is disposed at the front end of the upper grip and can easily be displaced with the thumb to lock or unlock the lower grip or movable blade.

The invention relates to hand grass shears of the type set forth in the 
preamble of claim 1. Such hand grass shears are known from DE-PS No. 
1,212,342. 
The invention is therefore based on the problem of improving hand grass 
shears of the type according to the preamble so that production is made 
more economical by simplifying the assembly, compact shears which are easy 
to operate being obtained which functionally fulfil all the expectations 
and largely eliminate any risk of injury. 
This problem is solved by the features set forth in the characterizing 
clause of claim 1. 
By the formation of the rotary head from plastic covering all the mechanism 
parts of the shears mechanism the danger that on operation thereof a 
finger can reach the transmission mechanism and be clamped therein is 
reduced. 
In the known hand grass shears the arresting member for the hand grips is 
formed as spring metal plate against which the front edge of the lower 
grip bears in the arresting position. The free leg of the spring can be 
pressed inwardly by spring pressure to enable the free lower edge of the 
lower grip to engage and by the opening spring the lower portion is 
pressed against the spring. When the grip portions are pressed together 
the arresting spring jumps out downwardly and the shears can be freely 
actuated. There is a danger here that when carelessly put down or 
unskillfully operated the shears can unintentionally open so that the 
grips and shear blades spring apart under the action of the expansion 
spring and this can lead to injuries. 
The invention is therefore also based on the problem of improving hand 
grass shears of the type according to claim 6 so that the arresting 
member, which is of simple construction and can be simply assembled, can 
be easily operated, its mode of operation being clearly apparent. 
This sub-problem is solved by the features set forth in the characterizing 
clause of claim 6. 
Further convenient developments of the invention are apparent from the 
subsidiary claims. 
The plastic construction of the swivel joint and the shears joint carried 
thereby permits an easy-moving soft pivoting, the swivel joint being able 
to engage reliably in various detent positions. It is provided in 
particular for the shear blades to pivot from a centre position towards 
both sides by 90.degree. in each case, in steps in each case of 
22.5.degree.. 
The advantage of the rotary head construction lies in the integration of 
various functions which will be set forth below: 
Easy assembly by engagement on the upper grip, utilizing the elasticity of 
the plastic. 
Rotational arresting in the range 0.degree.-180.degree., arresting every 
22.5.degree., utilizing the elasticity of the plastic. 
Stop 0.degree. and 180.degree. simultaneous compensation of the wing 
tolerances by resilient formation of the stop in the upper grip in the 
longitudinal direction. 
Swivel joint for upper blade is a plastic-plastic combination integrated in 
a screw-on tube. 
Accommodation of the lower blade by pivoting and simultaneous stabilizing 
of the rotary head by the lower blade. 
Covering of the entire mechanism swivel joint, pull rod, slide bush and 
mounting. On the rotary head at the top a grip knurling with 
directionarrows for adjustment is disposed.

The hand grass shears comprise an upper grip 10 moulded from plastic and a 
lower grip 14 which is pivotal with respect thereto via a swivel joint 12 
and which is completed via an integrally formed stirrup-like lower portion 
16 to give a closed ring. The lower grip also consists of plastic and is 
surrounded in the front region of the swivel joint 12 by the dish-shaped 
downwardly directed extension 18 of the upper grip 10. 
The upper grip comprises at its front upper end a slot 20 through which the 
lower leg 22 of a U-shaped cross-sectioned slide 24 can be inserted into 
the interior of the dish-shaped grip. The upper leg 26 of the slide runs 
on the somewhat set-back front upper side of the grip 10 so that its 
preferably knurled upper surface can be conviently pushed forwardly and 
rearwardly by the thumb of the hand enclosing the grips. At the front 
laterally the slide 24 is dish-shaped downwardly so that it aligns 
laterally and at the front with surfaces of the upper grip 10. 
The swivel joint 12 comprises a joint bush 28 which is inserted in aligning 
holes in the side walls of the lower grip dishes. Holes of the side walls 
of the upper grip dish aligning with the joint bush 28 are traversed by a 
centre-grooved dowel pin 30 which is led through the bush 28 and ensures 
the pivot connection of the two grips 10, 14. 
Between the side walls of the lower grip 14 a leg spring 32 is provided the 
purpose of which is to push the lower grip and the upper grip apart. This 
leg pin 32 constructed as wire spring is coiled annularly in its centre 
portion and drawn onto the joint bush 28. Its lower leg 34 bears on the 
inner side of the lower grip 14 and its upper slightly angled leg 36 bears 
against the lower leg 22 of the slide 24 and acts via the latter on the 
upper grip 10. By the spring force the slide is biased in its guide and 
between the slide and upper grip at any desired positions detent cams or 
detent depressions are provided which ensure the two shift positions of 
the slide apparent from FIGS. 1 and 2. These two detent positions are 
fixed by the spring 32. In the closed position according to FIG. 1 the 
lower grip is held by the lower leg 22 of the locking slide 24 which 
engages behind an extension 38 of the lower grip and holds the latter on 
the upper grip 10. In the advance position according to FIG. 2 the slide 
releases this extension and the lower grip can move apart under the action 
of the spring 32 as illustrated. 
Except for the leg spring 32 and the centre-grooved dowel pin 30 all the 
parts described above are injection moulded from plastic. The rotary head 
40 also consists of plastic. This rotary head serves to make the shear 
blades adjustable with respect to the grips about an axis 42 which extends 
parallel to the cutting plane of the blades and perpendicularly intersects 
the joint axis of the grip swivel joint 12. 
For mounting the rotary head 40 the upper grip extension 18 comprises at 
the front lower end side an integrally formed swivel joint bush 44 into 
which a bush 46 formed in the interior of the rotary head projects. At its 
end on the right in FIGS. 1 and 2 the bush 46 is provided with a step 48 
which extends over 180.degree. and into which a stop extension 50 of the 
upper grip extension 18 extends which limits the pivot movement from the 
position illustrated in FIGS. 1 and 2 to 90.degree. in each of the two 
swivel directions. 
The rotary head surrounds the swivel joint bush 44 with a dish-shaped cover 
52 which is provided with a grip knurling. 
In the interior of the cover 52 an inwardly projecting detent 54 engages 
behind a projection 56 projecting radially outwardly from the swivel joint 
bush, the rotary joint head thereby being secured from removal from the 
rotary joint bush 44. The assembly can however be effected simply in that 
the rotary joint head is inserted with its bush 46 into the swivel joint 
bush 44 and establishes the detent connection with the cover, the plastic 
yielding elastically and permitting the pushing on but because of the 
subsequently engaging detent faces preventing withdrawal. 
In the front portion of the dish-shaped rotary head 40 at the inside a 
bearing bush 58 is formed whose axis extends perpendicularly to the 
cutting plane of the blades. The fixed lower blade 60 is secured by means 
of a grooved dowel pin 62 and by means of screws 64 and 66 to the lower 
side of the rotary head 40. The screw 66 is screwed into the bearing bush 
58 forming the shear joint. 
The movable upper blade 68 is mounted pivotally on the bearing bush 58 by 
means of a slide bush 70 inserted into a hole of the shear blade. This 
slide bush 70 of plastic is integrally connected to a bearing flange 72 
which lies above the rear portion of the blade and is provided with a 
portion 74 engaging round the lower edge of the blade. The flange 72 runs 
along the lower side of the rotary head, the contact of the plastic 
surfaces ensuring a lower friction. The blade movement is outwardly 
limited by a stop 76 which projects upwardly from the flange 72 and 
cooperates with counterstops in the interior of the rotary head. 
Onto the bearing bush 58 a helical pressure spring 71 is fitted which 
biases the upper blade 68 against the lower blade 60. By the detent 
arrangement in any rotary position of the rotary head 40 movement of the 
upper blade with respect to the lower blade can be effected. The rotary 
position of the rotary head with respect to the upper grip extension can 
be fixed by rotary detents 80 between the rotary head and swivel joint 
bush 44, said detents preferably being disposed at angular intervals of 
22.5.degree.. 
The front bent end of a pull rod 78 led through the bush 46 is anchored in 
a hole of the upper blade laterally of the shears joint. 
The rear end of the pull rod 78 is supported axially in an adjustment bush 
82. Said adjustment bush 10 is screwed with an external thread into a 
transversely extending threaded hole of an adjustment pin 84 which is 
inserted into the two side walls of the lower grip running between the 
latter. The adjustment bush 82 comprises in the rear portion transverse 
slots 86 or key lugs with which it can be turned using a tool to enable 
the closure position of the blades to be fixed. The tool can be introduced 
through a hole 88 of the lower grip. 
To ensure that with an only relatively small angular rotation of the 
adjustment bush 82 even relatively large tolerances can be bridged, apart 
from the threaded connection between the adjustment bush and adjustment 
pin a further threaded connection is provided between the adjustment bush 
(internal thread) and pull rod 78 (external thread). These threads are 
formed as differential threads, the adjustment bush having at the inside 
for example a right-hand thread M5(p=0.8 mm) and at the outside a 
left-hand thread M8.times.l(p=l mm). 
The shears function as follows: by pushing the slide 24 forwardly the 
shears are unlocked and under the action of the spring 32 move into the 
position shown in FIG. 2. By actuating the lower grip 14 via the pull rod 
78 the upper blade 68 is moved with respect to the lower blade 60 and a 
cutting motion thus results. 
Both in the closed and locked position according to FIG. 1 and in the open 
position according to FIG. 2 the rotary head 40 can be turned with respect 
to the grips so that the ergonometrically most favourable handling of the 
shears can be obtained for any use. 
The shears according to FIGS. 3 and 4 are fundamentally made like the 
shears according to FIGS. 1 and 2 and differ from the latter substantially 
only in a simplification obtained by omitting the swivel joint. This means 
that the rotary head designated in FIG. 1 and 2 by reference numeral 40 is 
missing or integrally formed with the extension 18 of the upper grip. The 
rotary head 40 according to FIGS. 1 and 2 is thus replaced by a fixed 
bearing head 90 which is formed forwardly projecting on the lower portion 
of the extension 18 of the upper grip 10. This bearing head in turn 
comprises the downwardly extending bearing bush 58 for the upper blade 
which is actuated via the pull rod 78. The function is the same as in the 
shears according to FIGS. 1 and 2. 
FIG. 4 illustrates a simplified embodiment of the shears of FIG. 3 with a 
fixed cutting plane in which the lower grip 14a is formed without bottom 
portion as a hand lever having a hole 92 for suspension.