Improvements in Crabs and Pulley Blocks and other like Machines for Raising and Lowering Loads.
Year: 1890

page_text: Date of Application, 24th June, 1890
Complete Specification Left, 12th Mar., 1891-Accepted, 25th Apr.,
1891
PROVISIONAL SPECIFICATION.
Improvements in Crabs and Pulley Blocks and other like Machines
for Raising and Lowering Loads.
We, TANGYES LIMITED, of Cornwall Works, Soho, in the County of Stafford,
Engineers, and THOMAS MEACOCK, of No. 2, Waverhill Road, Handsworth, in
the County of Stafford, Mechanical Engineer, and THOMAS RAVENSCROFT, of
No. 2, Fern Villas, Bearwood Road, Smethwick, in the County of Stafford,
Mechanical Engineer, do hereby declare the nature of this invention to be as
follows :-
The said invention relates to crabs and pulley blocks and other like machines
for raising and lowering loads in which a pendent endless hand chain is employed
for raising the load. When it is wished to lower the load suspended by the
machine the brake is thrown out of action and the pendent loop of chain is drawn
up with great rapidity and acquires in its rising a wave like motion dangerous to
any person or thing in its vicinity.
The object of the said invention is to remove the danger referred to by dis-.
engaging the chain wheel from the pulley carrying the load when the brake is
thrown out of action and thereby to allow the load to descend without moving the
chain. The said invention has for its further object to give greater control over
the descending load than is possessed by the machines in question as ordinarily
constructed.
We will describe the improvements constituting the said invention as applied to
a crab.
Instead of fixing the hand chain wheel to its shaft as usual we connect the said
wheel and shaft by means of a sliding clutch on the shaft and fixed clutch box in
the boss of the chain wheel. The sliding clutch box is operated by a cam on a
shaft parallel to the shaft of the chain wheel. This cam consists of a circular disc
fixed on its shaft one half of the said disc being perpendicular to its axis the other
half being inclined a few degrees from the said perpendicular. The edge of this
cam disc engages in a groove in the sliding clutch. When the part perpendicular
to its axis is in the said groove the clutch is withdrawn from the clutch box and the
chain wheel disconnected from the load which descends without moving the chain
wheel. When the other or inclined part of the cam disc is engaged with the
groove of the clutch the said clutch is engaged with the clutch box. Thus by
giving to the shaft of the cam-disc a semi-rotation in one or other direction the
clutch can be thrown into or out of gear with the clutch box.
The shaft of the cam-disc has a pulley over which a cord or chain is passed and
to which it is affixed. This cord or chain has at one end a weight and when the
operator looses the cord or chain the said weight reverses the position of the cam-
disc pulley so that the chain wheel is geared to its shaft. But by pulling down-
wards the unweighted end of the cord the cam-disc may be made to perform a
semi-rotation and the chain wheel is ungeared from its shaft.
The action of the mechanism may be made automatic so that the throwing out
of gear of the brake may occur simultaneously with the ungearing of the chain
wheel from its shaft. This is effected by a projection formed on the cam shaft and
a short arm or projection on the brake the position of the projection on the cam
shaft being such that when it is about to operate on the projection on the brake and
throw the brake out of gear the part of the cam-disc which disconnects the chain
wheel from its shaft is brought into the groove in the clutch.
We do not limit ourselves to the particular means described for operating the
mechanism described as the said mechanism may be otherwise operated; for

page_text: example instead of employing a projection on the cam shaft to act on the arm on
the brake a lever and cord may be employed; a projection near the fulcrum of the
lever being brought by the depression of the long arm of the lever to act on the
brake and throw it out of action the short arm of the said lever at the same time
operating on a bell crank lever by which the clutch on the chain wheel shaft is
withdrawn from the clutch box in the boss of the chain wheel.
In order to give greater control over the descending load we employ two friction
pads in the brake strap instead of the one ordinarily employed. These friction
pads are situated at opposite points of the brake strap so that when the brake is
moved in the direction which withdraws the friction pad which is in operation the
opposite one shall be brought into operation. By the use of the two pads
described a more effectual control over the descending load is obtained than when
a single pad only is employed.
The application of the said improvements to crabs having a winch instead of an
endless pendent chain for raising the load and to machines other than crabs for
raising and lowering loads differs in no essential respect from their application to a
crab as hereinbefore described.
Dated this 24th day of June 1890.
W. T. WHITEMAN,
Agent for the Applicants.
COMPLETE SPECIFICATION.
Improvements in Crabs and Pulley Blocks and other like Machines
for Raising and Lowering Loads.
We, TANGYES LIMITED, of Cornwall Works, Soho, in the County of Stafford,
Engineers, and THOMAS MEACOCK, of No. 2, Waverhill Road, Handsworth, in the
County of Stafford, Mechanical Engineer, and THOMAS RAVENSCROFT, of No. 2,
Fern Villas, Bearwood Road, Smethwick, in the County of Stafford, Mechanical
Engineer, do hereby declare the nature of the said invention, and in what manner
the same is to be performed, to be particularly described and ascertained in and by
the following statement :-
The said invention relates principally to crabs and pulley blocks and other like
machines for raising and lowering loads in which a pendent endless hand chain is
employed for raising the load. When it is wished to lower the load suspended by
the machine the brake is thrown out of action and the pendent loop of chain is
drawn up with great rapidity and acquires in its rising a wave like motion dangerous
to any person or thing in its vicinity.
The object of the said invention is to remove the danger referred to by dis-
engaging the chain wheel from the pulley carrying the load when the brake is
thrown out of action and thereby allow the load to descend without moving the
chain. The said invention has for its further object to give greater control over
the descending load than is possessed by the machines in question as ordinarily
constructed.
We will describe the improvements constituting the said invention as applied to
a crab.
Instead of fixing the hand chain wheel to its shaft as usual we connect the said
wheel and shaft by means of a sliding clutch on the shaft and fixed clutch box in
the boss of the chain wheel. The sliding clutch box is operated by a cam on a
shaft parallel to the shaft of the chain wheel. This cam consists of a circular disc
fixed on its shaft, one half of the said disc being perpendicular to its axis, the other
half being inclined a few degrees from the said perpendicular. The edge of this
cam-disc engages in a groove in the sliding clutch. When the part perpendicular
to its axis is in the said groove the clutch is withdrawn from the clutch box and
the chain wheel disconnected from the load which descends without moving the
chain wheel. When the other or inclined part of the cam-disc is engaged with the

page_text: groove of the clutch the said clutch is engaged with the clutch box. Thus, by
giving to the shaft of the cam-disc a semi-rotation in one or other direction the
clutch can be thrown into or out of gear with the clutch box. The shaft of the
cam disc has a pulley over which a cord or chain is passed and to which it is
affixed. This cord or chain has at one end a weight and when the operator looses
the cord or chain the said weight reverses the position of the cam disc pulley so
that the chain wheel is geared to the shaft. But by pulling downwards the
unweighted end of the cord the cam-disc may be made to perform a semi-rotation
and the chain wheel is ungeared from its shaft.
The action of the mechanism may be made automatic so that the throwing out of
gear of the brake may occur simultaneously with the ungearing of the chain wheel
from its shaft. This is effected by a projection formed on the cam shaft and a
short arm or projection on the brake, the position of the projection on the cam
shaft being such that when it is about to operate on the projection on the brake
and throw the brake out of gear the part of the cam-disc which disconnects the
chain wheel from its shaft is brought into the groove in the clutch.
We do not limit ourselves to the particular means described for operating the
mechanism as the said mechanism may be otherwise operated: for example instead
of employing a projection on the cam shaft to act on the arm on the brake a lever
and cord may be employed, a projection near the fulcrum of the lever being brought
by the depression of the long arm of the lever to act on the brake and throw it out
of action the said lever at the same time operating on the clutch on the chain
wheel shaft to withdraw it from the clutch box in the boss of the chain wheel.
In order to give greater control over the descending load we employ two friction
pads in the brake strap instead of the one ordinarily employed. These friction
pads are situated at opposite points of the brake strap so that when the brake is
moved in the direction which withdraws the friction pad which is in operation the
opposite one shall be brought into operation. By the use of the two pads described,
a more effectual control over the descending load is obtained than when a single
pad only is employed.
The application of the said improvements to crabs having a winch instead of an
endless pendent chain for raising the load and to machines other than crabs for
raising and lowering loads differs in no essential respect from their application to a
crab as herein before described.
We will now proceed to describe with reference to the accompanying drawings
the manner in which the said invention is to be performed.
Figure 1 represents in side elevation and Figure 2 in plan and Figure 3 in
vertical section (drawn to a larger scale than Figures 1 and 2) our improvements
applied to an overhead or traversing crab worked by a pendent chain or chains,
the said Figures 1, 2 and 3 exhibiting the improvements for disconnecting the chain
wheel from the shaft of the pinion driving the pulley carrying the load and at
the same time automatically throwing the brake out of gear with the brake wheel
for lowering the load.
The same letters of reference indicate the same parts in Figures 1,
and 3.
a is the pendent chain passing over the chain wheel b for working the crab the
said chain wheel being loose upon the pinion shaft c but capable of being geared to or
ungeared from the said pinion shaft by the mechanism hereinafter described. A
small chain wheel 2 may be attached to the chain wheel b for facilitating the quick
raising of light loads. On the end of the pinion shaft c is a pinion d gearing with
the internal toothed wheel e carrying the pulley block by which the raising and
lowering of the weight carried by the loose or lower pulley block 9 are effected as
is well understood; is the brake wheel and i the brake strap which is automatically
operated for permitting of the lowering of the load in the manner hereinbefore
described. The mechanism for throwing the chain wheel 6 into and out of gear
with the pinion shaft e consists of a sliding clutch k on the said shaft c and a fixed
clutch box at the centre of the wheel b, the sliding clutch & being provided with
projections for engaging with similar projections on the clutch box . A sliding

page_text: clutch with its projections is shown drawn to a larger scale in Figures 6 and 7.
The sliding clutch k is grooved at m; n, n² is the cam or cam disc for operating the
sliding clutch the said cam disc being fixed on the shaft p parallel to and above
the pinion shaft c. It will be seen by an examination of Figure 3 that a portion,
say, about one half of the can marked n² is situated perpendicular to the shaft p
on which it is fixed while the other portion of the cam marked n is somewhat
inclined to the said shaft 1. The edge of the cam or cam disc n n² engages in the
groove m in the sliding clutch k. When the straight part of the cam disc engages
in the groove m the clutch k is withdrawn from the clutch box / and the chain
wheel is disconnected from the shaft e and the load may descend without moving
the chain wheel and the chain a upon it and the dangerous wave like motion
ordinarily imparted to the pendent loop of the chain a during the lowering of the
load is avoided.
When the inclined edge n of the cam like disc n, n² is engaged with the
groove m in the sliding clutch k the said clutch is moved towards the chain wheel b
and engaged with the clutch box las represented in Figure 3 and the chain wheel b
is put into gear with the lifting pinion shaft c. In this way, the semi-rotation of
the cam disc n, n² in one or other direction is made to throw the clutch k into or
out of gear with the clutch box l. The cam disc n, n² is partly rotated by a cord
(or chain) wound on the pulley n³ made in one piece with the cam disc n n² and
fixed to the shaft p. On the end of the cord 7 is a weight q² and when the
operator looses the unweighted end of the cord y the weight 2 reverses the position
of the cam pulley n³ or gives a semi-rotation to it so that the chain wheel is geared
with the shaft c when the cord g is in its normal position or is unoperated upon by
the attendant but by pulling down the end of the cord the cam pulley n³ and its
cam n n² are made to perform a semi-rotation and the chain wheel is ungeared
from its shaft c in the manner hereinbefore described.
The automatic throwing out of gear of the brake for lowering the load when the
chain wheel is thrown out of gear with the shaft c is effected by the part or arm r
on the cam disc shaft p acting upon the projections on the brake strap i; that is,
on the partial rotation of the shaft p by the pulley ³ the part of the said shaft
coming in contact with the projections on the brake strap takes the brake out of
action for the lowering of the load.
When by loosing the cord y the pulley n³ and shaft p have a back partial rotation
given to them; the part of the said shaft is removed from the projections on the
brake strap and the latter is again put into action for sustaining the load. The
cam-disc being in its normal position the chain wheel b is geared to or immediately
becomes geared to the pinion shaft c when the pendent chain a is pulled in either
direction.
Figure 4 represents in front elevation and Figure 5 in vertical section the
application of the said invention to a lifting pulley block worked by a pendent
chain, the operating of the sliding clutch and brake being effected by a lever and
cord and appliances connected therewith; Figures 6 and 7 represent elevations
taken at right angles to one another of the lever and cord arrangement drawn to a
larger scale.
The same letters of reference indicate the same parts in Figures 4, 5, 6 and 7;
a is the looped chain for working the loose chain wheel on the pinion shaft c;
d is the pinion; e the internal toothed wheel with which it gears; the lifting
pulley block and g the lower pulley block; k is the sliding clutch and the clutch
box as described with respect to the crab Figures 1, 2, and 3; t is the weighted
lever fixed upon the cam and brake operating shaft p and worked by the pulling
down of the cord t2 the overhanging weight on the opposite arm of the lever for
giving the return motion being marked t. On the unweighted arm of the lever /
is the operating cam 4 engaging with the sliding clutch k on the pinion shaft c by
fitting in the groove in the said sliding clutch. It will be seen by an examination
of Figure 7 that the operating cam t is slightly inclined to the shaft p so that as
the levert rises and falls a portion of the periphery of the cam further from or

page_text: nearer to the lever t engages in the groove in the sliding clutch k. The descent of
the lever thereby causes the inclined cam t to withdraw the sliding clutch from the
fixed clutch box and the ascent of the said lever causes the cam to engage the
clutch with the clutch box and thus ungear the chain wheel from or gear it to
the pinion shaft c as before described with respect to the crab. The lever tis.
provided with the shoulder to for acting upon the shoulder of the brake strap i.
By pulling down the hand cord t2 of the levert the said lever is depressed and with
it the cam t the curved portion of the cam operating upon and withdrawing the
clutch from the fixed clutch box and thereby ungearing the chain wheel b from
the pinion shaft c. By the further depression of the lever tits projection to bears
against the projection on the brake strap i and releases the latter from the brake
load descending. Thus, the pulling down of the lever t
to be disconnected from its shaft c and the brake at the
same time thrown out of gear. On loosing the cord 2 the operating parts are
returned to their normal positions by the action of the weight 3.
wheel to permit of the
causes the chain wheel
In combination with the brake strap i around the brake wheel h of the arrange-
ment shown in Figure 4 we have represented our improved double or compound
friction pad marked, y. A brake strap having our improved double or compound
friction pad is represented detached from the brake wheel in elevation and section
in Figure 8. It will be seen that the brake strap i is provided with two friction*
pads, y situated at opposite points; a being the self sustaining friction pad and
y the lowering friction pad. These pads are fitted into the inner face of the brake
strap in the manner represented in Figure 8. When the projection t on the
levert acts on the projection on the brake strap i the self sustaining pad c is
slightly moved from or eased off the brake wheel and the lowering friction pad y
is pressed upon the brake wheel. In this way the descent of the load can be very
efficiently controlled.
Figure 9 represents in elevation and Figure 10 in plan a crab worked by winches
or handles to which crab a modified arrangement of the invention for throwing the
handle shaft out of gear with the pinion shaft and for taking off the break for
lowering the load is applied. Figure 11 represents a cross section of a part of the
modified arrangement, drawn to a larger scale.
The same letters of reference indicate the same parts in Figures 9, 10, and 11;
2 is the handle shaft having square ends for receiving handles or winches. The
handle shaft 2 works through a sleeve c upon which the lifting pinions are keyed,
the said sleeve being the equivalent of the pinion shaft in the arrangements before
described; p is the cam and brake operating shaft above the pinion shaft or sleeve c
carrying the camp which engages with the groove in the sliding clutch working
on the handle shaft c².
By the sliding of the clutch & it may be engaged with and disengaged from the
sleeve or pinion shaft c for putting the handle shaft into or taking it out of gear
with the said sleeve or pinion. The cam and brake shaft p is operated by the
weighted hand lever ³ (see Figures 9 and 10) on its end. The weight praises the
hand lever p³, the sliding clutch k is thrown into gear with the sleeve c and the crab
is worked in the usual way by rotating the handles or winches on the shaft e². By
depressing the hand lever p³ the clutch k is withdrawn from the clutch box on the
sleeve and the handle shaft is thereby thrown out of gear with the said sleeve and
the brake strap is at the same time taken out of action as hereinbefore described for
lowering the load.
By this arrangement the handle shaft 2 and winches or handles upon it do not
rotate when lowering the load by the brake and the danger of accident from the
rotating winches which attend the use of the ordinary crabs is avoided.
The load in the first described arrangements may be lowered by the pendent
chains in lieu of the brake by not operating the hand cord and pulling the pendent
chain in an opposite direction to that which is necessary in lifting the load; and in
the arrangement Figures 9, 10, and 11 the body may be lowered by turning the
handle shaft 2 in the necessary direction the hand lever p³ being unoperated upon.

page_text: Instead of using sliding clutches put into and out of gear with the fixed clutch
boxes by means of engaging teeth they may be geared with the fixed clutch boxes
by frictional contact.
Having now particularly described and ascertained the nature of the said
invention, and the manner in which the same is to be performed, we declare that
we claim as the said invention of "Improvements in crabs and pulley blocks and
other like machines for raising and lowering loads :-
First: The construction and combination of parts hereinbefore described and
illustrated in Figures 1, 2 and 3 of the accompanying drawings for disconnecting
the chain wheel by which the crab, pulley block or other like machine is worked
from the pinion shaft of the said crab or machine and at the same time throwing
the brake out of action for lowering the load; that is to say, the combination or
arrangement of the cam or cam disc n, n² and pulley n³ worked by a weighted cord
or chain, with a sliding clutch on the pinion shaft carrying a loose chain wheel and
the combination of the said disconnecting mechanism with the shaft p and parts r
and s for releasing the brake strap substantially as described and illustrated.
Secondly The modified arrangement or combination of parts substantially as
herein before described and illustrated in Figures 4, 5, 6, and 7 of the accompanying
drawings in which a lever and cord and appliances connected therewith are used for
disconnecting the chain wheel from the pinion shaft and for taking the brake out of
action for lowering the load.
Thirdly The application or adaptation to crabs and other like machines worked
by winches or handles of the modified arrangement or combination of parts sub-
stantially as hereinbefore described and illustrated in Figures 9, 10, and 11 of the
accompanying drawings for disconnecting the handle or winch shaft from the pinion
shaft and for taking the break out of action for lowering the load.
Lastly-The combination with or adaptation to the brake straps of crabs, pulley
blocks and other like machines of two friction pads situated at opposite points of
the brake strap for the purpose and substantially as herein before described and
illustrated in Figures 4 and 8 of the accompanying drawings.
Dated the 11th day of March 1891.
TANGYES LIMITED,
W. J. PARKINS, Secretary.
MEACOCK.
THOMAS
THOMAS
RAVENSCROFT.