Sheffer MH SERIES - Manual (Page 2)

Piston rods through 4" diameter have a
minimum expected yield of 100,000 psi.
They are case hardened to 50 Rockwell C
to a depth of .030" for damage resistance.
They are then hard chrome plated for wear
and corrosion resistance. Larger diameter
rods have an expected minimum yield
of 50,000 to 60,000 psi depending on
diameter and are hard chrome plated.
Offers much longer fatigue life through
elimination of thread relief stress concentra-
tion point. Standard as Style 2 rod end on
all rod sizes through 2
1 / 2 " diameter. Studs
are pretorqued and locked in to prevent
loosening. They are machined from high
tensile steel and the threads rolled.
The steel tube is honed to an 8 to 16
microinch finish for low friction and long
seal and piston bearing life. Tube ends
are machined on the O. D. concentric with
the I. D. They are confined by the close
tolerance machining of the head and cap
which provides greater hoop strength.
Maximum strength is obtained through a
prestressed tie rod assembly.
Four wrench flats are provided as standard
for easy attachment. Spanner holes, in lieu
of flats, are standard on large diameter rods.
All pistons are machined from a fine grain
alloy cast iron. They are threaded directly
onto the piston rod, torqued, sealed and
locked in place with one or more set
screws.
The special piston seal is an endless
glass filled Teflon material with an O-ring
expander. One or more (depending on
bore size) bronze filled Teflon bearing
strips are also employed on this type piston
to eliminate metal-to-metal contact. This
type piston offers long life, low friction,
near zero leakage, and great tolerance for
side loading. It can be used successfully
on virtually any application.
Pressure activated O-ring seals are used
at rod gland and tube ends. Located to
eliminate extrusion and to provide positive
leak tight seal.
High load bearing bronze piloted into the
head. Located inboard of the seals to insure
a well lubricated bearing for the fastest
cycling applications. It need not be
removed for rod seal replacement.
The polyurethane wiper is designed to
wipe off abrasive dust and contaminants
on the retract stroke to insure long life for
packings, rod bearing, and piston rod.
Where the rod will be exposed to gummy
materials such as road tar, a metallic rod
scraper is available.
The polyurethane rod seal has a unique
design which incorporates the optimum
sealing properties of a U configuration with
the elastomeric properties of a compression-
type seal. The polyurethane material was
selected for toughness, abrasion resistance,
and the ability to resist extrusion under
rough service conditions.
Cushion pistons (29) are tapered to provide
gradual deceleration and eliminate shock
upon entrance. The Adjusting Screw
with fine threads (30, 40) provides a wide
range of adjustment. It is interchangeable
with the Ball Check (36, 46) permitting
field changes of position. Neither the
adjusting screw nor ball check plug project
beyond the head or cap surface.
When required, air bleeds are located
where they can be employed most
successfully – at the tube and head juncture.
The straight thread plugs are equipped
with metallic O-rings so they can be used
repeatedly with a good seal every time.
Easily removable for replacement of rod
seal and wiper. In most cases it is not
necessary to demount or disassemble the
cylinder. Easier to service since on removal
of the ductile iron gland, the piston rod
remains supported by the separate rod
bearing.
DIMENSIONALLY INTERCHANGEABLE TO MEET ANSI SPECIFICATIONS
Construction
ITEM QUANTITY
NUMBER
DESCRIPTION
REQUIRED
1 HEAD 1
2 CAP 1
3 PISTON ROD 1
3 A STUD – STYLE II THREAD THRU 2 1 / 2 " ROD DIA. 1
4 TUBE 1
5 TIE ROD 4
6 ROD GLAND RETAINER 1
6 A ROD GLAND AND RETAINER – SINGLE PIECE 1
9 PISTON – SLIPPER SEAL TYPE 1
10 RETAINER SCREW ‡
13 TIE ROD NUT 4
16 † TUBE SEAL 2
18 † PISTON SEAL – SLIPPER SEAL TYPE 1
18 A † EXPANDER – FOR SLIPPER SEAL 1
21 † ROD BEARING 1
22 † ROD GLAND SEAL 1
24 † ROD WIPER 1
25 † ROD SEAL 1
29 CUSHION PISTON – FRONT **
30 CUSHION ADJ. SCREW – FRONT (CROSS SLOT) **
31 SEAL – CUSHION ADJUSTING AND CUSHION
CHECK – FRONT
**
36 CUSHION CHECK BALL – FRONT **
38 CUSHION CHECK PLUG – FRONT **
40 CUSHION ADJ. SCREW – REAR (CROSS SLOT) **
41 SEAL – CUSHION ADJUSTING
AND CUSHION CHECK – REAR
**
46 CUSHION CHECK BALL – REAR **
48 CUSHION CHECK PLUG – REAR **
57 PISTON BEARING STRIP 1
58 AIR BLEED PLUG **
66 A BACK-UP WASHER – CUSHION ADJUSTING
AND CHECK – FRONT
**
66 B BACK-UP WASHER – CUSHION ADJUSTING
AND CHECK – REAR
**
70 ROD GLAND 1
‡ Retainer Screws required varies by bore and mount
† Recommended Spare Parts
** As required; specify if cushioned front, cushioned rear or cushioned both ends.
3 Piston Rod
4 Tube
5 Tie Rod Construction
7 Wrench Flats
9&18 Pistons & Piston Seals
21 Rod Bearing
24 Rod Wiper
25 Rod Seal
58 Air Bleeds (Optional)
70 Rod Gland
3A Studded Rod End
Parts List
16, 22 Static Seals
29 Cushions
1 MH-1