The capacity of spreader jaws has always been significantly lower than a
straight cylinder, mainly for keeping that accessory compact, I suspect.
The pulling cylinder accessory capacity ratings are typically also lower
rated.

The Blackhawks and similar models have been used for generations in autobody
collision repair and heavy equipment/industrial maintenance/service areas.
The spreader jaws are definitely handy because they're compact, and
generally more versatile than prybars or other methods of separating parts.

Spreader jaws' lower capacity is generally acceptable where working space
may be very limited.. and will generally cause little collateral damage,
unlike much higher capacity jaws-of-life emergency equipment, which
typically isn't intended to minimize damage.

Fittings machined from bar stock are the usual construction for the
hydraulics and also the mechanical extension tube couplers.

--
WB
..........


"axolotl" wrote in message
...

I brought home a Blackhawk "Porto Power" hydraulic hand pump with a set of
spreading jaws from yesterday's Cabin Fever. I would place the
manufacturing date as perhaps the 40's.
The rehab process brings up some questions:

The pump output port is connected to a 4" length of what appears to be
plain 3/8" iron pipe. This pipe connects to what appears to be a plain
iron union (?), with a reducing bushing for the hose on the other side of
the union. Are plain iron pipe fittings acceptable for high pressure
hydraulic use, or is this a kluge? (For my uses the pipe/union are coming
off.)

This style of pump is sold as a "10 Ton" pump. The piston on the jaws
appears to have an internal diameter of 1.5", so it would appear that I
would have to put 11000+ pounds of pressure on the fluid to get 10 Tons at
the piston. Pressure fittings and hoses for this use do not have that high
of a pressure rating. What am I missing?

thanks,

Kevin Gallimore